Absorbent articles comprising absorbent materials exhibiting deswell/reswell

ABSTRACT

The present invention relates to absorbent articles that include absorbent compositions which exhibit swelling, deswelling, and reswelling behavior. More specifically, absorbent compositions of this invention swell and absorb fluids after exposure to aqueous fluids, deswell and release fluids from the swollen absorbent compositions, and can also reswell and absorb fluids. The swelling-deswelling-reswelling behavior allows enhanced liquid distribution in absorbent composites and absorbent articles.

This patent application claims benefit under 35 U.S.C. 119(e) of U.S.Provisional Application Ser. No. 61/063,093 entitled Absorbent ArticlesComprising Absorbent Materials Exhibiting Deswell/Reswell filed in theU.S. Patent and Trademark Office on Jan. 30, 2008. The entirety ofprovisional application Ser. No. 61/063,093 is hereby incorporated byreference.

BACKGROUND

A superabsorbent polymer is a crosslinked partially neutralized polymerthat is capable of absorbing large amounts of aqueous liquids and bodyfluids, such as urine or blood, with swelling and the formation ofhydrogels, and of retaining the fluids under a certain pressure.Superabsorbent polymer compositions may include post-treatment of thesuperabsorbent polymer such as surface crosslinking, surface treatment,and other treatment. Superabsorbent polymer particles are particles ofsuperabsorbent polymers or superabsorbent polymer compositions. Unlessotherwise specified, the acronym “SAP” may be used herein in place ofsuperabsorbent polymer, superabsorbent polymer composition, andparticles thereof.

Commercially available superabsorbent polymer compositions typicallyinclude crosslinked polyacrylic acids or crosslinked starch-acrylic acidgraft polymers, in which some of the carboxyl groups are neutralizedwith sodium hydroxide solution or potassium hydroxide solution. Aprimary use of superabsorbent polymer compositions is in absorbentcomposites that are used in absorbent articles, such as diapers,training pants, incontinence products, or feminine care products. Forfit, comfort and aesthetic reasons, and from environmental aspects,there is an increasing trend to make absorbent articles smaller andthinner. This is often accomplished by reducing the content of highvolume fluff fiber typically present in these articles. To ensure aconstant total retention capacity of body fluids in the sanitaryarticles, the superabsorbent polymer composition content of theabsorbent articles is typically increased.

Fluid distribution in an absorbent composite is generally dependent on:the amount of free liquid available for distribution, the structure andmaterials of the absorbent composite, and a time factor. However,current absorbent composites useful in absorbent cores of absorbentarticles generally have inadequate (or less than desirable) fluiddistribution properties. Poor fluid distribution decreases the fullutility efficiency of absorbent composites as not all of thesuperabsorbent polymer composition absorbs the liquid (i.e., the SAP isnot fully utilized).

One potential solution known in the art for improving fluid distributionin an absorbent composite is to use superabsorbent polymer compositionshaving a slow absorbency rate. The theory for using slow absorbencysuperabsorbent polymer compositions is that there would be diminished ordelayed gel blocking and thereby would provide more free liquid, as wellas more time for the liquid to distribute away from the insult targetzone. However, although distribution may be enhanced using the slowsuperabsorbent, the absorbent composite typically does not providenecessary leakage protection.

As can be observed in the use of slow absorbency superabsorbent polymercompositions, there is a conflict between the functions of lockup anddistribution. One problem is that the time required to lockup liquidinto the superabsorbent polymer composition and open-up compositestructure by SAP swelling is relatively long. It is the free liquidwhich is in the target zone during a fluid insult period which isdifficult to get into the absorbent product core and is believed to beresponsible for leakage of liquid from an absorbent product while inuse. To reduce leakage, the superabsorbent material needs to lockupliquid at a rate similar to the liquid delivery rate so that anabsorbent product has adequate fluid handling functionality. However, ifthe superabsorbent polymer composition absorbs the liquid, thendistribution of liquid is reduced since there is no free liquid to bedistributed after fluid insult.

There is a need for an absorbent composite or an absorbent system thatdemonstrates the ability for a SAP to quickly lockup liquid and thengradually release this liquid so that it may be distributed to result indesirable leakage and distribution behavior. There is a further need foran absorbent article which exhibits enhanced fluid distributionproperties while maintaining enhanced lockup properties, therebymaximizing the absorbing capabilities of the absorbent article and/orits components thereof.

SUMMARY

In response to the needs discussed above, an absorbent article of thepresent invention comprises an absorbent composite or an absorbentsystem which exhibits swell/deswell/reswell behavior.

In some aspects, an absorbent composite comprises an absorbentcomposition. The absorbent composition comprises a SAP, a deswelltriggering agent (TA_(D)) and a reswell triggering agent (TA_(R)). Inaddition, the SAP, the TA_(D) and the TA_(R) are all selected fromeither solubility-based chemistry or neutralization-based chemistrygroupings. Furthermore, the absorbent composite has a top side and anopposing bottom side. In some aspects, the SAP, TA_(D) and TA_(R) aresubstantially uniformly distributed within the composite. In someaspects, the absorbent composite further comprises a target zone and aperimeter region; wherein the target zone comprises the SAP, TA_(D) andTA_(R); and wherein the perimeter region comprises substantially onlythe SAP. In some aspects, the the SAP is a superabsorbent polymercomposition. In some aspects, the TA_(D) comprises a first water-solublesolid chemical wherein the TA_(D) has a release profile for releasingthe water-soluble solid chemical, wherein the release profile isselected from a singular release profile or a sigmoidal release profile;wherein the TA_(R) comprises a second water-soluble solid chemical,wherein the reswell triggering agent has a sigmoidal release profile forreleasing the second water-soluble solid chemical; and wherein the firstwater-soluble chemical has a higher cumulative release than the secondwater-soluble chemical after exposure to aqueous fluid and before about100% release. In some aspects, the absorbent composite is present in anabsorbent article which further comprises a topsheet and a backsheet,wherein the absorbent composite is disposed between the topsheet and thebacksheet. In some aspects, the composite is present in an absorbentarticle selected from personal care absorbent articles, health/medicalabsorbent articles, household/industrial absorbent articles orsports/construction absorbent articles.

In some aspects, an absorbent composite has a fibrous matrix andcomprises a SAP, a deswell triggering agent (TA_(D)) and a reswelltriggering agent (TA_(R)). The SAP, the TA_(D) and the TA_(R) are allselected from either solubility-based chemistry or neutralization-basedchemistry groupings. In addition, the absorbent composite has a toplayer, a middle layer and a bottom layer where the middle layer isdisposed between the top layer and the bottom layer, and where each ofSAP, TA_(D) and TA_(R) is present in at least one of the layers. In someaspects, the the SAP is a superabsorbent polymer composition. In someaspects, the TA_(D) comprises a first water-soluble solid chemicalwherein the TA_(D) has a release profile for releasing the water-solublesolid chemical, wherein the release profile is selected from a singularrelease profile or a sigmoidal release profile; wherein the TA_(R)comprises a second water-soluble solid chemical wherein the reswelltriggering agent has a sigmoidal release profile for releasing thesecond water-soluble solid chemical; and wherein the first water-solublechemical has a higher cumulative release than the second water-solublechemical after exposure to aqueous fluid and before about 100% release.In some aspects, the middle layer of the absorbent composite comprisessubstantially only SAP; the top layer comprises substantially onlyTA_(D); and the bottom layer comprises substantially only TA_(R). Insome aspects, the middle layer of the absorbent composite comprisessubstantially only SAP; the top layer comprises substantially onlyTA_(D); the bottom layer comprises substantially only TA_(R); and atleast one of the TA_(D) and TA_(R) is located substantially only in atarget zone of the top layer and/or bottom layer, respectively. In someaspects, the the middle layer of the absorbent composite comprisessubstantially only SAP; and the top layer and the bottom layer eachcomprise substantially only TA_(D) and TA_(R) combined. In some aspects,the middle layer of the absorbent composite comprises substantially onlySAP; the top layer and the bottom layer each comprise substantially onlyTA_(D) and TA_(R) combined; and the TA_(D) and TA_(R) are locatedsubstantially only in a target zone of at least one of the top layer andbottom layer. In some aspects, the top layer, the middle layer, and thebottom layer of the absorbent composite each comprise substantially onlyone of the SAP, TA_(D) and TA_(R); where none of the layers is the same.In some aspects, the absorbent composite further comprises a firstintermediate layer and a second intermediate layer, wherein the firstintermediate layer is disposed between the top layer and the middlelayer, and wherein the second intermediate layer is disposed between themiddle layer and the bottom layer; wherein the top layer, the middlelayer, and the bottom layer each comprise substantially only SAP; andwherein the first intermediate layer and the second intermediate layereach comprise SAP, TA_(D) and TA_(R). In some aspects, the absorbentcomposite further comprises a first intermediate layer and a secondintermediate layer, wherein the first intermediate layer is disposedbetween the top layer and the middle layer, and wherein the secondintermediate layer is disposed between the middle layer and the bottomlayer; wherein the top layer, the middle layer, and the bottom layereach comprise substantially only SAP; wherein the first intermediatelayer comprises substantially only TA_(D); and wherein the secondintermediate layer comprises substantially only TA_(R). In some aspects,the absorbent composite is present in an absorbent article which furthercomprises a topsheet and a backsheet, wherein the absorbent composite isdisposed between the topsheet and the backsheet. In some aspects, thecomposite is present in an absorbent article selected from personal careabsorbent articles, health/medical absorbent articles,household/industrial absorbent articles or sports/construction absorbentarticles.

In some aspects, an absorbent system comprises a SAP, a deswelltriggering agent (TA_(D)) and a reswell triggering agent (TA_(R)). TheSAP, the TA_(D) and the TA_(R) are all selected from eithersolubility-based chemistry or neutralization-based chemistry groupings.The absorbent system further comprises an absorbent composite, a topdiscrete layer, and a bottom discrete layer; where the absorbentcomposite includes a fibrous matrix; and where the absorbent compositeis disposed between the top discrete layer and the bottom discretelayer. In some aspects, the SAP is a superabsorbent polymer composition.In some aspects, the TA_(D) comprises a first water-soluble solidchemical wherein the TA_(D) has a release profile for releasing thewater-soluble solid chemical, wherein the release profile is selectedfrom a singular release profile or a sigmoidal release profile; whereinthe TA_(R) comprises a second water-soluble solid chemical wherein thereswell triggering agent has a sigmoidal release profile for releasingthe second water-soluble solid chemical; and wherein the firstwater-soluble chemical has a higher cumulative release than the secondwater-soluble chemical after exposure to aqueous fluid and before about100% release. In some aspects, the absorbent composite comprisessubstantially only the SAP; the top discrete layer comprisessubstantially only the TA_(D); and the bottom discrete layer comprisessubstantially only the TA_(R). In some aspects, the absorbent compositecomprises substantially only the SAP; the top discrete layer comprisessubstantially only the TA_(D); the bottom discrete layer comprisessubstantially only the TA_(R); and at least one of the TA_(D) and theTA_(R) is located substantially only in a target zone of the topdiscrete layer and/or bottom discrete layer, respectively. In someaspects, the absorbent composite comprises substantially only the SAP;and the top discrete layer and the bottom discrete layer each comprisesubstantially only the TA_(D) and the TA_(R) combined. In some aspects,the the absorbent composite comprises substantially only the SAP; thetop discrete layer and the bottom discrete layer each comprisesubstantially only the TA_(D) and the TA_(R) combined; and the TA_(D)and the TA_(R) are located substantially only in a target zone of atleast one of the top discrete layer and/or bottom discrete layer. Insome aspects, the absorbent composite, the top discrete layer, and thebottom discrete layer each comprise exclusively only one of the SAP, theTA_(D) and the TA_(R). In some aspects, the absorbent system furthercomprises a first intermediate discrete layer and a second intermediatediscrete layer, wherein the first intermediate discrete layer isdisposed between the top discrete layer and the absorbent composite, andwherein the second intermediate discrete layer is disposed between theabsorbent composite and the bottom discrete layer; wherein the topdiscrete layer and the bottom discrete layer each comprise substantiallyonly SAP; wherein the absorbent composite comprises substantially SAP;and wherein the first intermediate discrete layer and the secondintermediate discrete layer each comprise the SAP, the TA_(D) and theTA_(R) combined. In some aspects, the absorbent system further comprisesa first intermediate discrete layer and a second intermediate discretelayer, wherein the first intermediate discrete layer is disposed betweenthe top discrete layer and the absorbent composite, and wherein thesecond intermediate discrete layer is disposed between the absorbentcomposite and the bottom discrete layer; wherein the top discrete layerand the bottom discrete layer each comprise substantially only the SAP;wherein the absorbent composite comprises substantially only SAP;wherein the first intermediate discrete layer comprises substantiallyonly the TA_(D); and wherein the second intermediate discrete layercomprises substantially only the TA_(R). In some aspects, the absorbentsystem is present in an absorbent article which further comprisescomprising a topsheet and a backsheet, wherein the absorbent system isdisposed between the topsheet and the backsheet. In some aspects, theabsorbent system is present in an absorbent article selected frompersonal care absorbent articles, health/medical absorbent articles,household/industrial absorbent articles or sports/construction absorbentarticles.

Numerous other features and advantages of the present invention willappear from the following description. In the description, reference ismade to exemplary aspects of the invention. Such aspects do notrepresent the full scope of the invention. Reference should therefore bemade to the claims herein for interpreting the full scope of theinvention. In the interest of brevity and conciseness, any ranges ofvalues set forth in this specification contemplate all values within therange and are to be construed as support for claims reciting anysub-ranges having endpoints which are real number values within thespecified range in question. By way of a hypothetical illustrativeexample, a disclosure in this specification of a range of from 1 to 5shall be considered to support claims to any of the following ranges:1-5; 1-4; 1-3; 1-2; 2-5; 2-4; 2-3; 3-5; 3-4; and 4-5.

FIGURES

The foregoing and other features, aspects and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims and accompanying drawings where:

FIG. 1 is an apparatus for the Swell/Deswell/Reswell Test;

FIG. 2 is a side view of an apparatus used for the Cradle Intake Test;

FIG. 3 is a plan view of one embodiment of an absorbent article that maybe used with the present invention;

FIG. 4 is a schematic diagram of one version of a method and apparatusfor producing an absorbent core;

FIG. 5 is a cross-section of an absorbent composite comprising SAP andtriggering agents distributed in a homogeneous fashion;

FIG. 6 is a cross-section of an absorbent composite comprising SAP andtriggering agents which are arranged to have superabsorbent polymercomposition rich regions and triggering agent rich regions in thez-direction;

FIG. 7 is a cross-section of an absorbent composite comprisingtriggering agents which are preferentially located in a target zone;

FIG. 8A is a cross-section of an absorbent system in which triggeringagents are located in discrete layers;

FIG. 8B is a cross-section of an absorbent system in which triggeringagents are located in a target zone in the discrete layers;

FIG. 8C is a cross-section of an absorbent system in which a deswelltriggering agent is located in a discrete layer above an absorbentcomposite while a reswell triggering agent is located in a discretelayer below the absorbent composite;

FIG. 8D is a cross-section of an absorbent system in which a deswelltriggering agent is located in a target zone of a discrete layer abovean absorbent composite while a reswell triggering agent is located in atarget zone of a discrete layer below the absorbent composite;

FIG. 8E is a cross-section of an absorbent system in which a reswelltriggering agent is located in a discrete layer above an absorbentcomposite while a deswell triggering agent is located in a discretelayer below the absorbent composite;

FIG. 8F is a cross-section of an absorbent system in which a reswelltriggering agent is located in a target zone of a discrete layer abovean absorbent composite while a deswell triggering agent is located in atarget zone of a discrete layer below the absorbent composite;

FIG. 8G is a cross-section of an absorbent system in which a reswelltriggering agent is located in an absorbent composite, a deswelltriggering agent is located in a discrete layer above the absorbentcomposite, and SAP is located in a discrete layer below the absorbentcomposite;

FIG. 8H is a cross-section of an absorbent system in which a deswelltriggering agent is located in an absorbent composite, a reswelltriggering agent is located in a discrete layer above the absorbentcomposite, and SAP is located in a discrete layer below the absorbentcomposite;

FIG. 8I is a cross-section of an absorbent system in which a reswelltriggering agent is located in an absorbent composite, SAP is located ina discrete layer above the absorbent composite, and deswell triggeringagent is located in a discrete layer below the absorbent composite;

FIG. 8J is a cross-section of an absorbent system in which a deswelltriggering agent is located in an absorbent composite, SAP is located ina discrete layer above the absorbent composite, and a reswell triggeringagent is located in a discrete layer below the absorbent composite;

FIG. 9 is a graphical plot of release profiles of poly(meth)acrylatecoated sulfamic acid;

FIG. 10 is a graphical plot of release profiles of poly(meth)acrylatecoated calcium formate;

FIG. 11 is a graphical plot of release profiles of cellulose acetate orcellulose acetate/ethyl cellulose coated calcium formate;

FIG. 12 is a graphical plot of release profiles of poly(meth)acrylatecoated sodium carbonate;

FIG. 13 is a graphical plot of release profiles of maleatedpolypropylene coated sodium carbonate;

FIG. 14 is a graphical plot of swell/deswell curves for a specific SAPproduct with various blends of deswell triggering agents;

FIG. 15 is a graphical plot of swell/deswell/reswell curves for aspecific SAP product and with various blends of deswell and reswelltriggering agents;

FIG. 16 is a graphical plot of swell/deswell/reswell curves forsuperabsorbent material SAP-B and with triggering agents TA_(D)-A andTA_(R)-B;

FIG. 17 is a graphical plot of swell/deswell/reswell curves for SAP-Cand SAP-D and with various blends of triggering agents TA_(D)-A andTA_(R)-B;

FIG. 18 is a graphical plot of swell/deswell/reswell curves for aspecific SAP product and with triggering agents TA_(D)-C and TA_(R)-A;

FIG. 19 is a graphical plot of swell/deswell/reswell curves forsuperabsorbent material SAP-B and with various blends of TA_(D) andTA_(R) triggering agents;

FIG. 20 is a graphical plot of swell/deswell/reswell curves forsuperabsorbent material SAP-D and with various blends of triggeringagents TA_(D)-F and TA_(R)-C;

FIG. 21 is a side view of Examples 41 to 44;

FIG. 22 is a side view of Examples 47 to 49;

FIG. 23 is a side view of Examples 52 to 54;

FIG. 24 is a top view of Examples 52 to 54;

FIG. 25A is a cross-section of an absorbent system in which SAP isuniformly distributed throughout the absorbent composite layer, and adeswell and reswell triggering agent is located substantially only in atleast one discrete layer located above and below the absorbent compositelayer;

FIG. 25B is a cross-section of an absorbent system in which the deswelland reswell triggering agent is substantially located in a target zoneof at least one discrete layer;

FIG. 25C is a cross-section of an absorbent system in which a deswelltriggering agent is located in a discrete layer located above theabsorbent composite layer and a reswell triggering agent is locatedsubstantially in a discrete layer located below the absorbent compositelayer;

FIG. 25D is a cross-section of an absorbent system in which thetriggering agents are each present in a target zone of a discrete layer;

FIG. 25E is a cross-section of an absorbent system in which a reswelltriggering agent is located in a discrete layer located above theabsorbent composite layer and a deswell triggering agent is locatedsubstantially in a discrete layer located below the absorbent compositelayer;

FIG. 25F is a cross-section of an absorbent system in which thetriggering agents are each present in a target zone of a discrete layer;

FIG. 25G is a cross-section of an absorbent system in which a reswelltriggering agent is located in an absorbent composite layer, a deswelltriggering agent is located in a discrete layer above the absorbentcomposite layer, and SAP is located in a discrete layer below theabsorbent composite layer;

FIG. 25H is a cross-section of an absorbent system in which SAP islocated in an absorbent composite layer, a deswell triggering agent islocated in a discrete layer above the absorbent composite layer, and areswell triggering agent is located in an additional layer located abovethe deswell triggering agent layer;

FIG. 25I is a cross-section of an absorbent system in which a reswelltriggering agent is located in an absorbent composite layer, SAP islocated in a discrete layer above the absorbent composite layer, anddeswell triggering agent is located in a discrete layer below theabsorbent composite layer; and

FIG. 25J is a cross-section of an absorbent system in which a SAP islocated in an absorbent composite layer, deswell triggering agent islocated in a discrete layer below the absorbent composite layer, and areswell triggering agent is located in an additional layer below thereswell triggering agent layer.

Repeated use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention.

TEST METHODS

Unless otherwise stated, all tests are conducted at a temperature of 21°C. and a relative humidity between 10% and 60%. Unless otherwise stated,the test fluid used in all the test methods described below is anaqueous 0.9 wt % sodium chloride solution (also referred to herein as“0.9 wt % saline”, or merely as “saline”) such as that available fromRicca Chemical Company, having a place of business in Arlington, Tex.,U.S.A.

Centrifuge Retention Capacity Test

The Centrifuge Retention Capacity (CRC) Test measures the ability of theSAP (or the absorbent composition) to retain liquid therein after beingsaturated and subjected to centrifugation under controlled conditions.The resultant retention capacity is stated as grams of liquid retainedper gram weight of the sample (g/g). The sample to be tested is preparedfrom particles that are pre-screened through a U.S. standard 30-meshscreen and retained on a U.S. standard 50-mesh screen. As a result, theSAP sample comprises particles sized in the range of about 300 to about600 microns. The particles may be pre-screened by hand or automatically.

The retention capacity is measured by placing about 0.2 grams of thepre-screened SAP (or the absorbent composition) sample into awater-permeable bag that will contain the sample while allowing a testsolution (0.9 weight percent sodium chloride in distilled water) to befreely absorbed by the sample. A heat-sealable tea bag material, such asthat available from Dexter Corporation (having a place of business inWindsor Locks, Conn., U.S.A.) as model designation 1234T heat sealablefilter paper is suitable. The bag is formed by folding a 12.7 cm by 7.6cm sample of the bag material in half and heat-sealing two of the openedges to form a 6.4 cm by 7.6 cm rectangular pouch. The heat seals areabout 0.6 inches inside the edge of the material. After the sample isplaced in the pouch, the remaining open edge of the pouch is alsoheat-sealed. Empty bags are also made to serve as controls. Threesamples are prepared for each sample to be tested.

The sealed bags are submerged in a pan containing the test solution atabout 23° C., making sure that the bags are held down until they arecompletely wetted. After wetting, the samples remain in the solution forabout 30 minutes, at which time they are removed from the solution andtemporarily laid on a non-absorbent flat surface.

The wet bags are then placed into the basket, wherein the wet bags areseparated from each other and are placed at the outer circumferentialedge of the basket, wherein the basket is of a suitable centrifugecapable of subjecting the samples to a G-force of about 350. Onesuitable centrifuge is a CLAY ADAMS DYNAC II, model #0103, having awater collection basket, a digital rpm gauge, and a machined drainagebasket adapted to hold and drain the flat bag samples. Where multiplesamples are centrifuged, the samples are placed in opposing positionswithin the centrifuge to balance the basket when spinning. The bags(including the wet, empty bags) are centrifuged at about 1,600 rpm(e.g., to achieve a target G-force of about 290 g-force with a variancefrom about 280 to about 300 g-force), for 3 minutes. G-force is definedas a unit of inertial force on a body that is subjected to rapidacceleration or gravity, equal to 9.75 m/sec² at sea level. The bags areremoved and weighed, with the empty bags (controls) being weighed first,followed by the bags containing the SAP or the absorbent compositionsamples. The amount of solution retained by the sample, taking intoaccount the solution retained by the bag itself, is the centrifugeretention capacity (CRC) of the SAP or the absorbent composition,expressed as grams of fluid per gram of SAP or absorbent composition.More particularly, the retention capacity is determined by the followingequation:sample/bag after centrifuge−empty bag after centrifuge−dry sample weightdry sample weight

The three samples of a desired SAP or absorbent composition are tested,and the results are averaged to determine the Centrifuge RetentionCapacity (CRC) of the material. Deviation of measurements of CRC may be±0.5.

Superabsorbent Polymer pH Test

This test measures the pH of a solution of SAP (or absorbentcomposition) in 0.9 wt % saline.

Materials Needed:

-   1. pH meter.-   2. pH electrode (Brinkman, Unitrode, PN#20910674 or equivalent)-   3. 250 ml beaker.-   4. Stir Plate capable of 500 rpm.-   5. Stir Bar (approximately 3 cm).-   6. 0.9 wt % Saline (Aqueous Sodium Chloride Solution, part number    7213.09-5 from Ricca, or equivalent).)-   7. Weigh boat.-   8. Balance (accurate to 0.0001 grams).-   9. Timer (NIST traceable).-   10. Graduated Cylinder (class A, 100 ml capacity)-   11. UltraPure water    Procedure:-   1. Obtain a 250 ml beaker.-   2. Measure 150 ml of 0.9 wt % saline into a graduated cylinder, and    pour the saline into the 250 ml beaker.-   3. Place a stir bar into the beaker.-   4. Place the weigh boat onto the balance and tare.-   5. Weigh 1.0 g±0.001 superabsorbent into the weigh boat.-   6. Pour the sample into the 250 ml beaker.-   7. Label the beaker with a sample I.D.-   8. Place the beaker onto the stir plate at 500 rpm.-   9. Start the timer and set for 3 minutes. Allow the sample to stir    for 3 min.-   10. When 3 min has expired, immerse the pH electrode into the    beaker.-   11. Continue to gently stir the sample.-   12. Set the timer for 6 min.-   13. Start the timer and measure the pH.-   14. When time (i.e., 6 min) has expired, record the measured value.-   15. Remove the pH electrode from the sample and rinse thoroughly    with ultrapure water.    Vortex Time Test    General Description

The vortex test measures the amount of time in seconds required for 2grams of a SAP or absorbent composition to close a vortex created bystirring 50 milliliters of saline solution at 600 revolutions per minuteon a magnetic stir plate. The time it takes for the vortex to close isan indication of the free swell absorbing rate of the SAP or absorbentcomposition.

Equipment & Materials

-   1. Beaker, 100 milliliter.-   2. Programmable magnetic stir plate, capable of providing 600    revolutions per minute (such as a Dataplate®, Model #721,    commercially available from PMC Industries).-   3. Magnetic stir bar without rings, 7.9 millimeters×32 millimeters,    Teflon covered (such as S/PRIM. brand single pack round stirring    bars with removable pivot ring, available from Baxter Diagnostics).-   4. Stopwatch.-   5. Balance, accurate to ±0.0.01 gram.-   6. Saline solution, 0.87 wt % Blood Bank Saline available from    Baxter Diagnostics (considered for this test to be the equivalent of    0.9 wt % saline).-   7. Weighing paper.-   8. Room with standard condition atmosphere (Temperature=23° C.±1° C.    and Relative Humidity=50%±0.2%).    Test Procedure:-   1. Measure 50 g±0.01 gram of the saline solution into the 100    milliliter beaker.-   2. Place the magnetic stir bar into the beaker.-   3. Program the magnetic stir plate to 600 revolutions per minute.-   4. Place the beaker on the center of the magnetic stir plate such    that the magnetic stir bar is activated. The bottom of the vortex    should be near the top of the stir bar.-   5. Weigh out 2 grams±0.01 gram of the polymer sample (i.e., SAP or    absorbent composition) to be tested on weighing paper.    -   NOTE: The sample is tested as received (i.e. as it would go into        an absorbent composite such as those described herein). No        screening to a specific particle size is done, though the        particle size is known to have an effect on this test.-   6. While the saline solution is being stirred, quickly pour the SAP    or absorbent composition to be tested into the saline solution and    start the stopwatch. The sample to be tested should be added to the    saline solution between the center of the vortex and the side of the    beaker.-   7. Stop the stopwatch when the surface of the saline solution    becomes flat and record the time.-   8. The time, recorded in seconds, is reported as the Vortex Time.    Swell/Deswell/Reswell Test

The Swell/Deswell/Reswell Test is intended to measure the liquidabsorption capacity of the absorbent composition versus time.

A suitable apparatus for this test is shown in FIG. 1. At one end ofthis apparatus is a fluid reservoir 210 containing 0.9% saline solution.The other end of the apparatus is a cylinder 280 for holding absorbentcomposition, and a small plastic box 240 for delivering saline solutionto the absorbent composition. For example, a Plexiglas cylinder(cylinder inner diameter=25 mm; height=33 mm) with screen filter clothon bottom (400 mesh=36 microns) can be used for the test. The top plateof box 240 has holes (ca. 1 mm diameter) on it. A piece of filter paper270 is placed between cylinder 280 and box 240 to ensure good contact ofabsorbent composition with saline solution. Box 240 is placed on a stand250 on an electronic balance 260 which is connected to a computer forrecording the weight change of absorbent composition during themeasurement. Box 240 is connected to reservoir 210 through a flexibletubing 230.

Prior to measurement, the height of reservoir 210 is adjusted to aproper level so that the liquid surface in reservoir 210 is at the samelevel as the top surface of box 240.

The Test is Started By:

-   1. adding 0.16 grams of the test sample into cylinder 280 and    placing a plastic piston on the top of the test sample;-   2. placing the cylinder on box 240 such that the bottom of the    cylinder is in contact with the liquid; and-   3. immediately starting recording the weight change of the test    sample.

The test is stopped after 240 minutes. The absorption capacity of theabsorbent material is calculated by dividing the liquid uptake by theweight of the superabsorbent polymer in the absorbent composition. Theswell/deswell/reswell curve is generated by plotting the absorptioncapacity versus time.

Release Profile Measurement Test

Release of Coated Sulfamic Acid Test

The release of sulfamic acid is determined by soaking the coatedsulfamic acid in deionized water at room temperature (23° C.) andmeasuring the pH of the solution using an ORION pH meter (Model No.290A) and a pH electrode (Model No. ORION 8-172BNWP).

The coated sulfamic acid (2.00 g) is sealed in a teabag. A heat-sealabletea bag material, such as that available from Dexter Corporation (havinga place of business in Windsor Locks, Conn., U.S.A.) as modeldesignation 1234T heat sealable filter paper is suitable. 1800 g ofdeionized water is added into a glass beaker with a magnetic stirringbar (10 mm×70 mm). The beaker is placed on a magnetic stirrer, and thesolution is stirred at 200 rpm. The teabag is soaked in the water. Asmall amount of liquid (about 20 g) is taken out at desired intervals(such as every 2 minutes, or every 5 minutes, or every 10 minutes, orevery 20 minutes, for example). The actual weight of solution removed isrecorded. The pH of the removed solution is measured with the pH meter.The data from the electrode is converted to concentration of releasedsulfamic acid by using the calibration curve generated with standardsolutions of sulfamic acid. The percentage of the released sulfamic acidis calculated based on the weight of released sulfamic acid and thetotal weight of sulfamic acid in the coated sample.

Release of Coated Calcium Formate Test

The release of calcium formate is determined according to the sameprocedure as for the Release of Coated Sulfamic Acid Test, except thatthe concentration of released calcium formate is measured using a VarianInductively Coupled Plasma (Model No. Vista MPX Radical).

Release of Coated Sodium Carbonate Test

The release of sodium carbonate is measured according to the sameprocedure as for the Release of Coated Sulfamic Acid Test, except thatthe released sodium carbonate is determined by following the release ofsodium ion using an Accumet sodium selective electrode (Available fromFisher Scientific, #13-620-503).

Cradle Intake Test

This test utilizes x-ray imaging to determine the amount of fluidlocated in various locations of the absorbent composite or the absorbentsystem. X-ray imaging is known in the art as discussed, for example, inan article entitled “Fluid Distribution: comparison of X-ray ImagingData” by David F. Ring, Oscar Lijap and Joseph Pascente in NonwovensWorldmagazine, summer 1995, at pages 65-70, which is incorporated hereinby reference in a manner that is consistent herewith. Generally, thisprocedure compares the gray scale x-ray images of a wet and dry samplein order to calculate the liquid content at various locations. Suchx-ray systems are available, for example, from Precision X-ray Inc.,having a place business located at 31 Business Park Drive, Branford,Conn., U.S.A. as model no. 10561 HF 100 with enclosure. This system mayuse image analysis software from Optimus Inc., having a place ofbusiness located at Ft. Collins, Colo., U.S.A. as BIO-SCAN OPTIMATE S/NOPM4101105461 version 4.11, or equivalent. The x-ray system is operatedwith an exposure time of 1.5 seconds, with a tube voltage of 40 Kv andcurrent of 16 mA. The absorbent composite or absorbent system sample iskept in the cradle configuration during x-ray imaging.

Procedure:

-   1. Absorbent composite samples (or absorbent system samples),    measuring 7.6 cm wide by 38.1 cm, are placed into a U-shaped cradle    (FIG. 2) such that the mid-point of the length direction is    positioned at the bottom of the cradle.-   2. A peristaltic pump (such as a Masterflex-Digistaltic model    #7526-00 available from Cole-Parmer, having a place of business in    Barrington, Ill., U.S.A.) is used to deliver 70 cc of 0.9% saline    solution at a rate of 15 cc/sec. Saline solution is dispensed    through a nozzle with a 3.0 mm diameter opening. Liquid is added at    a target point which corresponds to the mid-point of the sample in    the length and width direction.-   3. 50 minutes after the liquid delivery an x-ray image of the sample    is taken to measure how the saline solution is distributed    throughout the absorbent composite or absorbent system.-   4. 60 minutes after the first liquid delivery, a second liquid    delivery and x-ray image is taken, repeating steps 2-3.-   5. 60 minutes after the second liquid delivery, a third liquid    delivery and x-ray image is taken, repeating steps 2-3.-   6. Three replicates of each sample are tested and an average fluid    distribution profile is determined by averaging the x-ray images of    each of the replicates.    Horizontal Distribution Test-   1. A sample (absorbent composite or absorbent system of the present    invention) 2.5 cm wide by 38.1 cm is placed onto a flat, horizontal    surface-   2. 0.9 wt % saline solution is added to the sample at a target point    corresponding to the midpoint of the length and width direction. The    saline solution is added by use of a funnel and stopcock system    suspended over the sample. The saline solution is added at a rate    sufficient such that minimal pooling occurs on the surface of the    sample.-   3. 20 cc of 0.9 wt % saline solution is added to the sample and    allowed to be absorbed into and distributed through the sample.-   4. 50 minutes after the liquid delivery, the length of the sample    which is wetted by the saline solution is observed visually.-   5. 60 minutes after the first liquid delivery, a second liquid    delivery and wetted length measurement is conducted, repeating steps    3-4.-   6. 60 minutes after the second liquid delivery, a third liquid    delivery and wetted length measurement is conducted, repeating steps    3-4.-   7. 3 replicates of each sample are tested and the average wetted    length after each insult is determined.    Horizontal Intake and Distribution Test

This test utilizes x-ray imaging to determine the amount of fluidlocated in various locations of a sample (i.e., absorbent composite orabsorbent system). X-ray imaging is known in the art as discussed, forexample, in an article entitled “Fluid Distribution: comparison of X-rayImaging Data” by David F. Ring, Oscar Lijap and Joseph Pascente inNonwovens Worldmagazine, summer 1995, at pages 65-70, which isincorporated herein by reference in a manner that is consistentherewith. Generally, this procedure compares the gray scale x-ray imagesof a wet and dry sample in order to calculate the liquid content atvarious locations. Such x-ray systems are available, for example, fromPrecision X-ray Inc. (having a place business located at 31 BusinessPark Drive, Branford, Conn., U.S.A.) as model no. 10561 HF 100 withenclosure. This system may use image analysis software from Optimus Inc.(having a place of business located at Ft. Collins, Colo., U.S.A.) asBIO-SCAN OPTIMATE S/N OPM4101105461 version 4.11, or equivalent. Thex-ray system is operated with an exposure time of 1.5 seconds, with atube voltage of 40 Kv and current of 16 mA. The absorbent sample is keptin a horizontal, flat configuration during x-ray imaging.

Procedure:

-   1. A sample (absorbent composite or absorbent system), 7.6 cm wide    by 38.1 cm long is placed onto a flat, horizontal surface.-   2. A fixture comprising a 2.5 cm inner diameter tube, with a flanged    bottom which can rest on the sample is placed such that the center    of the inner diameter of the tube corresponds with the midpoint of    the length and width direction of the sample.-   3. 70 cc of saline solution is poured into the tube and allowed to    soak into sample.-   4. 50 minutes after the liquid delivery, the length of the sample    that is wetted by the saline solution is measured using x-ray    densitometry images.-   5. 60 minutes after the first liquid delivery, a second liquid    delivery and wetted length determination is conducted, repeating    steps 3-4.-   6. 60 minutes after the second liquid delivery, a third liquid    delivery and wetted length determination is conducted, repeating    steps 3-4.-   7. Three replicates of each sample are tested and the average wetted    length after each insult is determined.    Mannequin Test

The Mannequin Test procedure involves placing an absorbent article ontoa static mannequin representing the torso of an appropriate sized human.Suitable mannequins can be obtained, for example, from CoutrayConsulting, having a place of business located in Douai, France. Fluidis added to the product by way of tubing running through the interior ofthe mannequin. Once liquid leaks from the product, it is detected bysensors that stop the liquid addition to that product. The amount ofliquid added to the product when it leaks can be determined by weighingthe products before and after they are removed from the mannequin.

Products can be evaluated for their leakage performance using theMannequin Test procedure disclosed herein. Saline leakage performance istested on a static mannequin system. The static mannequin system can beused in a forced leakage protocol in which the mannequin remains in thesame position for the evaluation, in this case in the prone position(simulating the condition when the product user is laying on his/herstomach). The mannequin system uses a computer controlled set of valvesand sensors to automatically deliver fluid to a particular mannequin anddetermine when a leakage event has occurred. The amount of liquid addedand the frequency of liquid addition can be controlled. For a particulartest, these conditions can be fixed. When a product has leaked, asindicated by a sensor or visually seeing the leak, it is removed andweighed to determine the amount of fluid that has been absorbed (i.e.load at leak). After removal of the products from the mannequins, theproducts can be x-rayed for fluid distribution.

This test utilizes x-ray imaging to determine the amount of fluidlocated in various locations of the absorbent system. X-ray imaging isknown in the art as discussed, for example, in an article entitled“Fluid Distribution: comparison of X-ray Imaging Data” by David F. Ring,Oscar Lijap and Joseph Pascente in Nonwovens Worldmagazine, summer 1995,at pages 65-70, which is incorporated herein by reference in a mannerthat is consistent herewith. Generally, this procedure compares the grayscale x-ray images of a wet and dry sample in order to calculate theliquid content at various locations. Such x-ray systems are available,for example, from Precision X-ray Inc. (having a place business locatedat 31 Business Park Drive, Branford, Conn., U.S.A.) as model no. 10561HF 75 with enclosure. This system may use image analysis software fromOptimus Inc. (having a place of business located at Ft. Collins, Colo.,U.S.A.) as BIO-SCAN OPTIMATE S/N OPM4101105461 version 6.1, orequivalent.

The Procedure is as Follows:

-   1. The diaper to be tested is placed onto an appropriately sized    infant mannequin which is equipped with tubing that allows delivery    of saline solution to the product in an anatomically accurate    location.-   2. The mannequin, with the diaper installed, is placed into a prone    (on the stomach) position.-   3. 70 cc of saline solution is added at a target location,    corresponding to 11.4 cm from the front edge of the absorbent    system. For the other half of the products to be tested, 35 cc of    saline solution is added to the same target location.-   4. The saline solution is added at 15 cc/sec using a peristaltic    pump (such as a Masterflex-Digistaltic model #7526-00 available from    Cole-Parmer, having a place of business in Barrington, Ill., U.S.A.)    and an anatomically representative male genital with a nozzle inside    diameter of 3.1 mm.-   5. Every hour an additional 70 cc insult of saline solution is added    to the product, using the above pump and nozzle system.-   6. When the product leaks liquid, the product is removed from the    mannequin.-   7. After laying the used product out flat and horizontally, an x-ray    image is taken of the used product. Exposure time, voltage, and    current during the x-ray images are 5.0 seconds, 23 kV, and 14 ma.    The area where liquid exists in the product is determined from the    x-ray image

DEFINITIONS

It should be noted that, when employed in the present disclosure, theterms “comprises,” “comprising” and other derivatives from the root term“comprise” are intended to be open-ended terms that specify the presenceof any stated features, elements, integers, steps, or components, andare not intended to preclude the presence or addition of one or moreother features, elements, integers, steps, components, or groupsthereof.

The term “absorbent article” generally refers to devices which canabsorb and contain fluids. For example, personal care absorbent articlesrefer to devices which are placed against or near the skin to absorb andcontain various fluids discharged from the body.

The term “absorbent composite” is used herein to refer to a mixture ofSAP and/or triggering agents with a carrier matrix including, but notlimited to, fibers, foams, nonwovens, films, or other carrier materials.

The term “absorbent composition” refers to a combination of SAP and atleast one triggering agent to achieve swell-deswell-reswell behavior ofthe present invention.

The term “absorbent system” is used herein to refer to a combination ofan absorbent composite and at least one additional discrete layer whichcomprises at least one triggering agent and/or SAP in which such layeris in direct physical contact with a surface of the absorbent composite.The additional discrete layer may consist solely of the SAP and/ortriggering agent, or may be a surge layers adhesive layer, tissue layer,foam layer, adhesive/tissue laminate, and the like which comprises theSAP and/or triggering agent.

The term “active agent” refers to the chemical released by a triggeringagent which interacts with a SAP to cause deswell and/or reswellbehavior.

The term “coating” is used herein to mean a layer of any substancespread over a surface.

The term “complexing” is used herein to describe the forming ofmolecules by the combination of ligands (such as anions) and metal ions.

The term “crosslinked” used in reference to SAP refers to any means foreffectively rendering normally water-soluble materials substantiallywater-insoluble but swellable. Such a crosslinking means may include,for example, physical entanglement, crystalline domains, covalent bonds,ionic complexes and associations, hydrophilic associations such ashydrogen bonding, hydrophobic associations, or Van der Waals forces.

The term “current” when used as a time reference refers to a time periodof approximately the priority date of the present application.

The term “desorb” is used herein to mean the release of fluids from aSAP.

The term “deswell” is used herein to refer to the decrease in size of aSAP that occurs while fluids are being desorbed from the SAP.

The term “disposable” is used herein to describe items such as absorbentarticles that are not intended to be laundered or otherwise restored orreused (e.g., as an absorbent article) after a single use.

The term “dry” when referring to a SAP generally refers to the SAPhaving less than about 10% moisture.

The term “health/medical absorbent articles” includes a variety ofprofessional and consumer healthcare products including, but not limitedto, products for applying hot or cold therapy, medical gowns (i.e.,protective and/or surgical gowns), surgical drapes, caps, gloves, facemasks, bandages, wound dressings, wipes, covers, containers, filters,disposable garments and bed pads, medical absorbent garments, underpads,and the like.

The term “household/industrial absorbent articles” includes constructionand packaging supplies, products for cleaning and disinfecting, wipes,covers, filters, towels, disposable cutting sheets, bath tissue, facialtissue, nonwoven roll goods, home-comfort products including pillows,pads, mats, cushions, masks and body care products such as products usedto cleanse or treat the skin, laboratory coats, cover-alls, trash bags,stain removers, topical compositions, pet care absorbent liners, laundrysoil/ink absorbers, detergent agglomerators, lipophilic fluidseparators, and the like.

The term “multivalent ions” is used herein to mean an electricallycharged atom or group of atoms formed by the loss or gain of multipleelectrons, as a cation (positive ion), which is created by a loss of oneor more electrons, or as an anion (negative ion), which is created by again of one or more electrons.

The terms “particle,” “particulate,” and the like, when used withrespect to the absorbent composition of the present invention refer tothe form of discrete units. The units may comprise flakes, fibers,agglomerates, granules, powders, spheres, pulverized materials, or thelike, as well as combinations thereof. The particles may have anydesired shape: for example, cubic, rod-like, polyhedral, spherical orsemi-spherical, rounded or semi-rounded, angular, irregular, etc. Shapeshaving a high aspect ratio, like needles, flakes, and fibers, are alsocontemplated for inclusion herein. The terms may also include anagglomeration comprising more than one individual particle, particulate,or the like. Additionally, a particle, particulate, or any desiredagglomeration thereof may be composed of more than one type of material.

The term “personal care absorbent article” includes, but is not limitedto, absorbent articles such as diapers, diaper pants, baby wipes,training pants, absorbent underpants, child care pants, swimwear, andother disposable garments; feminine care products including sanitarynapkins, wipes, menstrual pads, menstrual pants, panty liners, pantyshields, interlabials, tampons, and tampon applicators; adult-careproducts including wipes, pads such as breast pads, containers,incontinence products, and urinary shields; clothing components; bibs;athletic and recreation products; and the like.

The term “polymer” includes, but is not limited to, homopolymers,copolymers, for example, block, graft, random, and alternatingcopolymers, terpolymers, etc., and blends and modifications thereof.Furthermore, unless otherwise specifically limited, the term “polymer”shall include all possible configurational isomers of the material.These configurations include, but are not limited to isotactic,syndiotactic, and atactic symmetries.

The term “polyolefin” as used herein generally includes, but is notlimited to, materials such as polyethylene, polypropylene,polyisobutylene, polystyrene, ethylene vinyl acetate copolymer, and thelike, the homopolymers, copolymers, terpolymers, etc., thereof, andblends and modifications thereof. The term “polyolefin” shall includeall possible structures thereof, which include, but are not limited to,isotatic, synodiotactic, and random symmetries. Copolymers includeatactic and block copolymers.

The term “release profile” as used herein refers to the quantity oramount of active agent (which cause a SAP to deswell or reswell) that isreleased into solution from the triggering agents as a function of time,that are typically illustrated as the cumulative release, expressed as apercentage of the total amount of active agent present in the triggeringagents, as a function of time and may be shown as a graphical summary ofthe releasing of the active agent into solution of a particularsubstance.

The term “reswell” is used herein to refer to the growth in size of theSAP that occurs while fluids are being absorbed by the SAP afterdeswell.

The term “SAP” may be used herein in place of superabsorbent polymer,superabsorbent polymer composition, and particles thereof.

The term “singular release profile” generally refers to a releaseprofile that is represented by a concave downward curve. The initialrelease rate is fast but gradually becomes slower.

The term “sigmoidal release profile” refers to a release profile that isrepresented by a concave upward then concave downward curve. It isgenerally characterized by an initial lag phase, a steep intermediaterelease phase, and a slow final release phase.

The term “solubility product constant” is a simplified equilibriumconstant (Ksp) defined for equilibrium between a solid and itsrespective ions in a solution. Its value indicates the degree to which acompound dissociates in water. The higher the solubility productconstant, the more soluble the compound. The Ksp expression for a saltis the product of the concentrations of the ions, with eachconcentration raised to a power equal to the coefficient of that ion inthe balanced equation for the solubility equilibrium.

The term “sports/construction absorbent articles” includes headbands,wrist bands and other aids for absorption of perspiration, absorptivewindings for grips and handles of sports equipment, and towels orabsorbent wipes for cleaning and drying off equipment during use.

The term “superabsorbent polymer composition” refers to a superabsorbentpolymer comprising a surface additive in accordance with the presentinvention.

The terms “superabsorbent polymer” and “superabsorbent polymerpreproduct” refer to a material that is produced by conducting all ofthe steps for making a superabsorbent polymer as described herein, upthrough drying the material, and coarse grinding in a crusher.

The term “surface crosslinking” means that the level of functionalcrosslinks in the vicinity of the surface of a SAP particle generally ishigher than the level of functional crosslinks in the interior of theSAP particle. As used herein, “surface” describes the outer-facingboundaries of the particle. For porous SAP particles, exposed internalsurfaces also are included in the definition of surface.

The term “swell” is used herein to refer to the growth in size of a SAPthat occurs while fluids are being absorbed by the SAP.

The term “superabsorbent” refers to water-swellable, water-insolubleorganic or inorganic materials capable, under the most favorableconditions, of absorbing at least about 10 times their weight, or atleast about 15 times their weight, or at least about 25 times theirweight in an aqueous solution containing 0.9 wt % sodium chloride.

The term “target zone” refers to an area of an absorbent core where themajority of a fluid insult, such as urine, menses, or bowel movement,initially contacts. In particular, for an absorbent core with one ormore fluid insult points in use, the insult target zone refers to thearea of the absorbent core extending a distance equal to about 10% toabout 30% of the total length of the composite from each insult point inboth directions. The term “perimeter region” refers to the area outsidethe target zone.

The term “thermoplastic” describes a material that softens when exposedto heat and which substantially returns to a non-softened condition whencooled to room temperature.

The term “triggering agent” is used herein to refer to a material thatincludes an active agent chemical that when released causes a SAP todeswell or to reswell as desired.

The term “% by weight” or “wt %” or variations thereof, when used hereinand referring to components of a SAP, is to be interpreted as based onthe weight of dry SAP, unless otherwise specified herein.

These terms may be defined with additional language in the remainingportions of the specification.

DETAILED DESCRIPTION

Absorbent articles of the present invention can comprise an absorbentcomposite or absorbent system. In some aspects, the absorbent compositeor absorbent system can function as the absorbent core component of anabsorbent article. Thus, an absorbent article of the present inventioncan have an absorbent core, and in some aspects can optionally include atopsheet and/or a backsheet. In some aspects, the absorbent core can bedisposed between a topsheet and a backsheet. In some aspects, theabsorbent core comprises an absorbent composite or absorbent system thatincludes the absorbent composition of the present invention. In someaspects, the absorbent composite or absorbent system functions as theabsorbent article. In some aspects, the absorbent article is desirablydisposable.

In some aspects, the absorbent article of the present inventioncomprises an absorbent composition which utilizes multifunctionalmaterials to enhance distribution of fluids. Current commercial SAPfunctions to swell and absorb fluids. The absorbent article of thepresent invention can include SAP which swells and absorbs fluids, andwhich also can deswell and release fluids away from the swollen SAP, andwhich can further reswell and absorb fluids from an additional fluidinsult.

The absorbent articles of the present invention can comprise SAP andtriggering agents. The triggering agents of this invention compriseactive agent chemicals which trigger superabsorbent polymers to deswelland/or reswell.

In some aspects, the SAP of this invention swells during absorption offluids and, in some particular aspects, may be triggered to deswell andrelease fluid by at least one triggering agent. The free liquid releasedby the triggered deswelling may then be free to be distributed away fromthe swollen SAP where the initial insult occurred in the absorbentarticle. In further aspects, the deswelled SAP may be triggered toreswell and absorb fluid by a reswell triggering agent, such as fluidduring a subsequent insult. The swelling-deswelling-reswelling cycleallows insult liquid to be locked up, released, and then distributedthroughout an absorbent composite or absorbent system, and then becapable of reswelling on subsequent liquid insults, fully utilizing thefull absorbent capabilities of an absorbent article while minimizingleakage.

In some aspects of this invention, a SAP may be triggered to deswell andreswell by a change in the solubility of the triggering agents. In oneaspect, an absorbent composition may comprise a SAP having anionicfunctional groups, a deswell triggering agent comprising a firstwater-soluble chemical comprising cations X having an ionized valence oftwo or more, and a reswell triggering agent comprising a secondwater-soluble chemical comprising anions Y, wherein the cations X of thefirst water-soluble chemical are capable of complexing with the anions Yof the second water-soluble chemical to form a salt having a solubilityproduct constant Ksp<10⁻⁵.

In some aspects of the present invention, triggering agents having aselected release profile for release of an active agent from thetriggering agents, and a method for the preparation of such triggeringagents, is also included. Different absorbent applications, and/ortriggering agents, may require different types of release profiles suchas a singular release profile or a sigmoidal release profile. In oneaspect, the release profile of the triggering agents may be controlledby selecting appropriate coating polymers that are applied on thesurface of the water-soluble chemicals. In another aspect, the releaseprofile may also be controlled by adjusting the coating process forapplying coating polymers.

In some aspects, the absorbent composition of the absorbent articlesdemonstrating swelling-deswelling-reswelling behavior and a method ofcontrolling the timing of the swelling-deswelling-reswelling cycle arealso included. An aspect of this invention is an absorbent articlehaving an absorbent composition comprising a SAP, a deswell triggeringagent having a selected release profile for releasing a firstwater-soluble solid chemical, and a reswell triggering agent having arelease profile for releasing a second water-soluble solid chemical fromthe reswell triggering agent, wherein the first water-soluble chemicalhas higher cumulative release than the second water-soluble chemicalafter exposure to aqueous fluid, such as 0.9 wt % saline, and before thefirst water-soluble chemical is about 100% released. The timing forabsorbing/releasing fluid may be controlled by selecting suitablerelease profiles for the deswell and reswell triggering agents, and/orby adjusting the release rates of the deswell and reswell triggeringagents, and/or by altering the absorption rate of the SAP, and/or byaltering the mixing ratio of the SAP, the deswell triggering agent, andthe reswell triggering agent. The acronyms “TA_(D)” and “TA_(R)” may beused in place of “deswell triggering agent” and “reswell triggeringagent” respectively herein.

In some aspects of this invention, SAP having improved absorptioncapacity efficiency and mass efficiency in theswelling-deswelling-reswelling cycle are included. Absorption capacityefficiency improvement generally refers to the increase of the swellingor reswelling capacity of an absorbent composition compared with theabsorbent composition comprising a current commercial SAP. The massefficiency improvement refers to the utilization of a lesser percentageof reswell triggering agent with respect to the SAP while achieving thesame amount of deswelling liquid.

Mass efficiency improvement also refers to the utilization of a lesserpercentage of reswell triggering agent with respect to SAP whileachieving the same amount of reswelling capacity. The capacityefficiency improvement may be achieved by adjusting the degree ofneutralization and crosslinking of SAP, and/or by altering theabsorption speed of SAP, and/or by altering the mixing ratio of the SAP,the deswell triggering agent, and the reswell triggering agent. The massefficiency improvement may also be achieved in the same manner.

To gain a better understanding of the present invention, attention isdirected to FIG. 3 for exemplary purposes showing an exemplary absorbentarticle of the present invention in the form of a diaper. It isunderstood that the present invention is suitable for use with variousother absorbent articles, including but not limited to other personalcare absorbent articles, health/medical absorbent articles,household/industrial absorbent articles, sports/construction absorbentarticles, and the like, without departing from the scope of the presentinvention.

FIG. 3 illustrates a diaper 130. The diaper 130 is shown in FIG. 3 in anunfolded, flat-out, uncontracted state (i.e., with all elastic inducedgathering and contraction removed). Portions of the structure arepartially cut away to more clearly show the interior construction of thediaper 130, with the surface of the diaper 130 which contacts the wearerfacing the viewer. FIG. 3 illustrates a disposable diaper 130 as havinga front region 132, a rear region 134 and a crotch region 136 locatedbetween the front and rear regions. The diaper 130 comprises a backsheet138, a topsheet 140, and an absorbent core 142 situated between thebacksheet and the topsheet. The outer edges of the diaper 130 define aperiphery 144 with transversely opposed, longitudinally extending sideedges 146; longitudinally opposed, transversely extending end edges 148;and a system of elastomeric gathering members, such as a systemincluding leg elastics 150 and waist elastics 152. The longitudinal sideedges 146 define the leg dispensing orifices 154 for the diaper 130, andoptionally, are curvilinear and contoured. The transverse end edges 148are illustrated as straight, but optionally, may be curvilinear. Thediaper 130 may also comprise additional components to assist in theacquisition, distribution and storage of bodily waste. For example, thediaper 130 may comprise a transport layer, such as described in U.S.Pat. No. 4,798,603, issued to Meyer et al., or a surge management layer,such as described in European Patent Application Publication No. 0 539703, published May 5, 1993, each of which is incorporate herein byreference in a manner that is consistent herewith.

The diaper 130 generally defines a longitudinally extending lengthdimension 156, and a laterally extending width dimension 158. The diaper130 may have any desired shape, such as rectangular, I-shaped, agenerally hourglass shape, or a T-shape, for example.

The backsheet 138 defines a length and a width that, in the illustratedversion, coincide with the length and width of the diaper 130. Theabsorbent core 142 generally defines a length and width that are lessthan the length and width of the backsheet 138, respectively. Thus,marginal portions of the diaper 130, such as marginal sections of thebacksheet 138, may extend past the transversely opposed, longitudinallyextending terminal side edges 160 and/or the longitudinally opposed,transversely extending terminal end edges 162 of the absorbent core 142to form side margins 164 and end margins 166 of the diaper 130. Thetopsheet 140 is generally coextensive with the backsheet 138, but mayoptionally cover an area that is larger or smaller than the area of thebacksheet, as desired. The backsheet 138 and topsheet 140 are intendedto face the garment and body of the wearer, respectively, while in use.The topsheet 140 and the backsheet 138 can, for example, be joined toeach other in at least a portion of the diaper periphery 144 byattachment mechanisms (not shown) such as adhesive bonds, sonic bonds,thermal bonds, pinning, stitching, or a variety of other attachmenttechniques known in the art, as well as combinations thereof.

The topsheet 140 suitably presents a bodyfacing surface which iscompliant, soft feeling, and non-irritating to the wearer's skin.Further, the topsheet 140 may be less hydrophilic than the absorbentcore 142, to present a relatively dry surface to the wearer, and issufficiently porous to be liquid permeable, permitting liquid topenetrate readily through its thickness. A suitable topsheet 140 may bemanufactured from a wide selection of web materials, such as porousfoams, reticulated foams, apertured plastic films, natural fibers,synthetic fibers (for example, polyester or polypropylene fibers), or acombination of natural and synthetic fibers. The topsheet 140 issuitably employed to help isolate the wearer's skin from liquids held inthe absorbent core 142.

Various woven and nonwoven fabrics may be used for the topsheet 140. Forexample, the topsheet 140 may be composed of a meltblown or spunbondedweb of polyolefin fibers. The topsheet 140 may also be a bonded-cardedweb composed of natural and/or synthetic fibers. The topsheet 140 may becomposed of a substantially hydrophobic material, and the hydrophobicmaterial may, optionally, be treated with a surfactant, or otherwiseprocessed, to impart a desired level of wettability and hydrophilicity.Specifically, the topsheet 140 may be a nonwoven, spunbond,polypropylene fabric.

The backsheet 138 may suitably be composed of a material which is eitherliquid permeable or liquid impermeable. It is generally desirable thatthe backsheet 138 be formed from a substantially liquid impermeablematerial. For example, a typical backsheet 138 can be manufactured froma thin plastic film or other flexible liquid impermeable material.Further, the backsheet 138 may be formed of a woven or nonwoven fibrousweb layer which has been totally or partially constructed or treated toimpart a desired level of liquid impermeability to selected regions thatare adjacent or proximate the absorbent core 142. Still further, thebacksheet 138 may optionally be composed of micro-porous “breathable”material that permits vapors to escape from the absorbent core 142 whilestill preventing liquid exudates from passing through the backsheet 138.

The absorbent core 142 may comprise a matrix of hydrophilic fibers, suchas a web of cellulosic fluff, mixed with particles of absorbentcomposition, such as SAP and triggering agents of the present invention.In some aspects, the absorbent core 142 comprises a mixture of absorbentcomposition particles and wood pulp fluff. The wood pulp fluff may beexchanged with synthetic polymeric, meltblown fibers or with acombination of meltblown fibers and natural fibers. The absorbentcomposition particles may be substantially homogeneously mixed with thefibers or may be non-uniformly mixed.

As representatively illustrated in FIG. 3, the diaper 130 may include apair of containment flaps 157 that are configured to provide a barrierto the lateral flow of body exudates. The containment flaps 157 may belocated along the longitudinally extending side edges 146 of the diaper130 adjacent the side edges of the absorbent core 142. Each containmentflap 157 typically defines an unattached edge that is configured tomaintain an upright, perpendicular configuration in at least the crotchregion 136 of the diaper 130 to form a seal against the wearer's body.The containment flaps 157 may extend longitudinally along the entirelength of the absorbent core 142 or may only extend partially along thelength of the absorbent core 142. When the containment flaps 157 areshorter in length than the absorbent core 142, the containment flaps 157can be selectively positioned anywhere along the side edges 146 of thediaper 130 in the crotch region 136. The containment flaps 157 mayextend along the entire length of the absorbent core 142 to bettercontain the body exudates.

The diaper 130 may further include elastics at the end edges 148 andside edges 146 of the diaper 130 to further prevent leakage of bodyexudates and support the absorbent core 142. The diaper 130 may alsoinclude a pair of waist elastics 152 that are connected to the end edges148 of the diaper 130. The leg elastics 150 and waist elastics 152 aregenerally adapted to fit about the legs and waist of a wearer in use tomaintain a positive, contacting relationship with the wearer toeffectively reduce or eliminate the leakage of body exudates from thediaper 130.

The elastics may be adhered to the backsheet 138 in a stretchedposition, or they may be attached to the backsheet 138 while thebacksheet 138 is pleated, such that elastic constrictive forces areimparted to the backsheet 138. The leg elastics 150 may also includesuch materials as polyurethane, synthetic and natural rubber. The waistelastics 152 may be formed by elastic strands attached to the backsheet138 or they may be formed by attaching separate pieces of stretchablematerials to the waist regions of the article.

The disposable absorbent articles can, but need not necessarily,comprise fasteners 167 for securing the absorbent article about thewaist of the wearer. The illustrated version of the diaper 130 comprisessuch fasteners 167. In at least one aspect, the fasteners 167 aresituated in the rear region 134 of the diaper 130, and are locatedinboard each longitudinal extending side edge 146. The fasteners 167 maybe configured to encircle the hips of the wearer and engage thebacksheet 138 of the front region 132 of the diaper 130 for holding thediaper on the wearer. Suitable fasteners are well known to those ofskill in the art and can comprise adhesive tape tab fasteners, hook andloop fasteners, mushroom fasteners, snaps, pin, belts and the like, andcombinations thereof. Desirably, the fasteners 167 are releasablyengageable directly with the garment-facing surface of the backsheet138. Desirably, the fasteners 167 comprise a mechanical fasteningsystem.

By way of illustration only, various materials and methods forconstructing other absorbent articles are disclosed in PCT PatentApplication WO 00/37009 published Jun. 29, 2000 by A. Fletcher et al.;U.S. Pat. No. 4,940,464 issued Jul. 10, 1990 to Van Gompel et al.; U.S.Pat. No. 5,766,389 issued Jun. 16, 1998 to Brandon et al., and U.S. Pat.No. 6,645,190 issued Nov. 11, 2003 to Olson et al. which areincorporated herein by reference in a manner that is consistent (i.e.,not in conflict) herewith.

In some aspects of the present invention, the absorbent article cancomprise an absorbent composite or absorbent system of the presentinvention, which can function as the absorbent core 142. The absorbentcomposite or absorbent system can have various components, particularlythe absorbent components, having corresponding configurations ofstructure, configurations of absorbent capacities, configurations ofdensities, configurations of basis weights and/or configurations ofsizes which are selectively constructed and arranged to provide desiredcombinations of liquid intake time, absorbent saturation capacity,absorbent retention capacity, liquid distribution, shape maintenance,and aesthetics. By incorporating its various features andconfigurations, alone and in operative combinations, the article of theinvention can provide an improved absorbent composite or absorbentsystem having a desired combination of swell, deswell and/or reswellcapabilities. The article can be less susceptible to premature leakage,and can provide improved comfort and fit, improved protection andincreased confidence to the wearer.

In some aspects, the absorbent composite or absorbent system of thepresent invention comprises fibers, such as fluff, or more particularlycellulosic fibers. Such cellulosic fibers may include, but are notlimited to, chemical wood pulps such as sulfite and sulfate (sometimescalled Kraft) pulps, as well as mechanical pulps such as ground wood,thermomechanical pulp and chemithermomechanical pulp. More particularly,the pulp fibers may include cotton, other typical wood pulps, celluloseacetate, debonded chemical wood pulp, and combinations thereof. Pulpsderived from both deciduous and coniferous trees can be used.Additionally, the cellulosic fibers may include such hydrophilicmaterials as natural plant fibers, milkweed floss, cotton fibers,microcrystalline cellulose, microfibrillated cellulose, or any of thesematerials in combination with wood pulp fibers. Suitable cellulosicfluff fibers can include, for example, NB480 (available fromWeyerhaeuser Co.); NB416, a bleached southern softwood Kraft pulp(available from Weyerhaeuser Co.); COOSABSORB S, a bleached southernsoftwood Kraft pulp (available from Bowater Inc., a business havingoffices located in Greenville, S.C. U.S.A.).; SULPHATATE HJ, achemically modified hardwood pulp (available from Rayonier Inc., abusiness having offices located in Jesup, Ga., U.S.A.); NF 405, achemically treated bleached southern softwood Kraft pulp (available fromWeyerhaeuser Co.); and CR 1654, a mixed bleached southern softwood andhardwood Kraft pulp (available from Bowater Inc.). In some aspects, thewood pulp fluff may be exchanged with or combined with syntheticpolymeric, meltblown fibers or with a combination of meltblown fibersand natural fibers.

The absorbent composite or absorbent system can be formed using methodsknown in the art. While not being limited to the specific method ofmanufacture, the absorbent composite or absorbent system can utilize ameltblown process and, in some aspects, can further be formed on ameltblown or coform line. Exemplary meltblown processes are described invarious patents and publications, including NRL Report 4364,“Manufacture of Super-Fine Organic Fibers” by V. A. Wendt, E. L. Booneand C. D. Fluharty; NRL Report 5265, “An Improved Device For theFormation of Super-Fine Thermoplastic Fibers” by K. D. Lawrence, R. T.Lukas and J. A. Young; and U.S. Pat. No. 3,849,241 to Butin et al. andU.S. Pat. No. 5,350,624 to Georger et al., all of which are incorporatedherein by reference in a manner that is consistent herewith.

To form “coform” materials, additional components are mixed with themeltblown fibers as the fibers are deposited onto a forming surface. Forexample, the absorbent composition of the present invention and fluff,such as wood pulp fibers, may be injected into the meltblown fiberstream so as to be entrapped and/or bonded to the meltblown fibers.Exemplary coform processes are described in U.S. Pat. No. 4,100,324 toAnderson et al.; U.S. Pat. No. 4,587,154 to Hotchkiss et al.; U.S. Pat.No. 4,604,313 to McFarland et al.; U.S. Pat. No. 4,655,757 to McFarlandet al.; U.S. Pat. No. 4,724,114 to McFarland et al.; U.S. Pat. No.4,100,324 to Anderson et al.; and U.K. Patent GB 2,151,272 to Minto etal., each of which is incorporated herein by reference in a manner thatis consistent herewith. Absorbent, elastomeric meltblown webs containinghigh amounts of superabsorbent are described in U.S. Pat. No. 6,362,389to D. J. McDowall, and absorbent, elastomeric meltblown webs containinghigh amounts of superabsorbent and low superabsorbent shakeout valuesare described in pending U.S. patent application Ser. No. 10/883,174 toX. Zhang et al., each of which is incorporated herein by reference in amanner that is consistent herewith.

One example of a method of forming an absorbent composite or absorbentsystem for use in the present invention is illustrated in FIG. 4. Thedimensions of the apparatus in FIG. 4 are described herein by way ofexample. Other types of apparatus having different dimensions and/ordifferent structures may also be used to form the absorbent composite orabsorbent system. As shown in FIG. 4, elastomeric material 72 in theform of pellets can be fed through two pellet hoppers 74 into two singlescrew extruders 76 that each feed a spin pump 78. The elastomericmaterial 72 may be a multicomponent elastomer blend available under thetrade designation VISTMAXX 2370 from ExxonMobil Chemical Company (abusiness having offices located in Houston, Tex., U.S.A.), as well asothers mentioned herein. Each spin pump 78 feeds the elastomericmaterial 72 to a separate meltblown die 80. Each meltblown die 80 mayhave 30 holes per inch (hpi). The die angle may be adjusted anywherebetween 0 and 70 degrees from horizontal, and is suitably set at about45 degrees. The forming height may be at a maximum of about 16 inches,but this restriction may differ with different equipment.

A chute 82 having a width of about 24 inches (61 cm) wide may bepositioned between the meltblown dies 80. The depth, or thickness, ofthe chute 82 may be adjustable in a range from about 0.5 to about 1.25inches (1.3 cm to 3.2 cm), or from about 0.75 to about 1.0 inch (1.9 cmto 2.5 cm). A picker 144 connects to the top of the chute 82. The picker144 is used to fiberize the pulp fibers 86. The picker 144 may belimited to processing low strength or debonded (treated) pulps, in whichcase the picker 144 may limit the illustrated method to a very smallrange of pulp types. In contrast to conventional hammermills that usehammers to impact the pulp fibers repeatedly, the picker 144 uses smallteeth to tear the pulp fibers 86 apart. Suitable pulp fibers 86 for usein the method illustrated in FIG. 4 include those mentioned herein, suchas NB480 (available from Weyerhaeuser Co., a business having officeslocated in Federal Way, Wash., U.S.A.).

At an end of the chute 82 opposite the picker 144 is a SAP feeder 88.The feeder 88 can pour the SAP 90 of the present invention into a hole92 in a pipe 94 which then feeds into a blower fan 96. Past the blowerfan 96 is a length of 4-inch (10-cm) diameter pipe 98 sufficient fordeveloping a fully developed turbulent flow at about 5,000 feet perminute, which allows the SAP particles 90 to become distributed. Thepipe 98 widens from a 4-inch (10-cm) diameter to the 24-inch by0.75-inch (61 cm by 1.9 cm) chute 82, at which point the SAP 90 mixeswith the pulp fibers 86 and the mixture falls straight down and getsmixed on either side at an approximately 45-degree angle with theelastomeric material 72. The mixture of SAP 90, pulp fibers 86, andelastomeric material 72 falls onto a wire conveyor 100 moving from about14 to about 35 feet per minute. However, before hitting the wireconveyor 100, a spray boom 102 optionally sprays an aqueous surfactantmixture 104 in a mist through the mixture, thereby rendering theresulting absorbent composite 44 wettable. The surfactant mixture 104may be a 1:3 mixture of GLUCOPON 220 UP (available from CognisCorporation having a place of business in Cincinnati, Ohio, U.S.A.) andAHCOVEL Base N-62 (available from Uniqema, having a place of business inNew Castle, Del., U.S.A.). An under wire vacuum 106 is positionedbeneath the conveyor 100 to assist in forming an absorbent composite 44.

The absorbent composite or absorbent system of the present inventionincludes a desired amount of absorbent composition, such as the SAP andthe triggering agents of the present invention. In some aspects, theabsorbent composition has the property or capability of rapidlyabsorbing large amounts of fluids such as urine or other body fluids.Since the absorbent composition according to the invention has theability to quickly lockup liquid and then gradually release this liquidso that the liquid may be distributed throughout the absorbentcomposite, it can result in higher utility efficiency of absorbentcomposites, so that they are more desirably employed in thinner articleswith reduced basis weight, or highly shaped absorbent composites withnarrow crotch for better fit, when compared to conventional currentabsorbent products. In some aspects, such absorbent composites orabsorbent systems may also be suitable for use as a homogeneousabsorbent composition layer without fluff or other fiber content withinthe diaper construction, resulting in the possibility of thinner hygienearticles.

The absorbent composition of the present invention can also be employedin absorbent articles that are suitable for further uses. In particular,the absorbent composition of this invention may be used in absorbentcomposites or absorbent systems for absorbent products for water oraqueous liquids, desirably in constructions for absorption of bodyfluids, in foamed and non-foamed sheet-like structures, in packagingmaterials, in constructions for plant growing, as soil improvementagents, or as active compound carriers. For this, they are processedinto a web by mixing with paper or fluff or synthetic fibers or bydistributing the absorbent composition particles between substrates ofpaper, fluff, or non-woven textiles, or by processing into carriermaterials. They are further suited for use in absorbent articles such aswound dressings, packaging, agricultural absorbents, food trays andpads, and the like.

In one aspect of this invention, the SAP of the present invention iscapable of swelling and absorbing fluid and, when a deswell triggeringagent is applied, deswelling and releasing fluids, and when a reswelltriggering agent is applied, reswelling and absorbing fluid again.“Swelling” refers to the growth in size of the SAP that occurs whilefluids are being absorbed by the SAP. For swelling to occur in the SAP,fluids must be absorbed; therefore, to say that a SAP is swelling alsomeans the SAP is absorbing fluid. “Deswelling” refers to the decrease insize of the SAP that occurs while fluids are being desorbed from theSAP. For deswelling to occur in a SAP, the absorbed fluids must bedesorbed, or released from the SAP; therefore, to say a SAP isdeswelling also means the SAP is releasing liquid. “Reswelling” refersto the increase in size once again of the SAP that occurs while fluidsare being absorbed by the SAP after deswell. For reswelling to occur inSAP, fluids must be re-absorbed; therefore, to say that a SAP isreswelling also means the SAP is again absorbing fluid.

SAPs of this invention are capable of deswelling and desorbing fluidsafter interacting with triggering agent. In one aspect of thisinvention, a deswell triggering agent functions after the SAP issaturated, or substantially saturated, with absorbed liquid. The deswelltriggering agent causes the SAP to deswell and release a desired portionof the absorbed liquid.

The SAP and the triggering agents may be present in, or on a surface of,an absorbent material in a weight ratio from about 1:0.01 to about 1:10,such as from about 1:0.1 to about 1:2. In some aspects, the resultingabsorbent composite or absorbent system may include from about 10 toabout 90 wt % of SAP, such as from about 20 to about 80 wt % of SAP;from about 5 to about 60 wt % of a deswell triggering agent; and fromabout 5 to about 60 wt % of a reswell triggering agent.

The triggering agents as described herein may be of a size that, whenincorporated into a personal care product such as a baby diaper, cannotreadily migrate out of the composite product. Generally, the triggeringagents may have a particle size of from about 5 μm to about 1000 μm,such as from about 50 μm to about 1000 μm, or from about 100 μm to about850 μm, or from about 150 μm to about 850 μm.

Triggering agents may be applied to the absorbent composite or absorbentsystem by means of blending, encapsulation, coating, attaching using abinder material, printing, laminating, strategically blending, and/orplacing in specific pockets of the composites, combinations of these, orother means. Triggering agents may have time delayed effects, and onlystart to function (i.e., release active agents) when such effects areeliminated.

In some aspects of this invention, at least one of said triggeringagents is spatially separated from the SAP and/or from the othertriggering agent.

The SAP of this invention swells during absorption of fluids and, insome aspects, may be triggered to deswell and release fluid by thedeswell triggering agent. The deswelled SAP can also be triggered toreswell and absorb fluid by a reswell triggering agent. In some aspects,the swelling-deswelling-reswelling cycle may be repeated multiple times.

In some aspects of the invention, certain SAPs may be more effectivewhen used with certain triggering agents. To maximize the benefits ofthe present invention, it may be desirable to categorize the SAPs andthe triggering agents into groupings based loosely on somecharacteristic, such as chemistry and/or release profile, for instance.Thus, in some aspects, the SAPs and the triggering agents may be groupedas follows: solubility chemistry and neutralization chemistry.Preferrably, a SAP, a deswell triggering agent and a reswell triggeringagent will all be selected from a single grouping.

The solubility-based chemistry grouping includes chemicals capable ofachieving low solubility product constants (i.e., Ksp). In some aspects,the solubility-based chemistry grouping can include the following: a SAPhaving anionic functional groups; a deswell triggering agent comprisinga first water-soluble chemical comprising cations X having an ionizedvalence of two or more; and a second triggering composition comprising asecond water-soluble chemical comprising anions Y; where the cations Xof the first water-soluble chemical are capable of complexing with theanionic functional groups of the SAP; and the anions Y of the secondwater-soluble chemical are capable of complexing with the cations X toform a salt having a solubility product constant Ksp<10⁻⁵.

The neutralization-based chemistry grouping includes chemicals capableof controlling the degree of neutralization (DN) of the SAP. In someaspects, the neutralization-based chemistry grouping can include thefollowing: a) a SAP comprising partially neutralized crosslinkedpoly(acrylic acid) wherein from about 40 molar percent to about 60 molarpercent of the acidic functional groups are neutralized, having a pHless than about 6.0; b) a deswell triggering agent comprising a firstwater-soluble chemical; and c) a reswell triggering agent comprising asecond water-soluble chemical having pH of about 10 or more; where whenthe absorbent composition is contacted with an aqueous fluid, the SAPexhibits swell-deswell-reswell behavior and the resultant swollen SAPhas a pH higher than the SAP of a).

In addition, a release-based chemistry grouping can include chemicalscapable of controlling the release profile of the solubility-basedchemistry and/or neutralization-based chemistry groups described above.In some aspects, the release-based chemistry grouping can include thefollowing: a SAP comprising an optional blowing agent; a deswelltriggering agent comprising a first water-soluble solid chemical wherethe deswell triggering agent has a release profile for releasing thewater-soluble solid chemical (active agent) from the triggeringcomposition, wherein the release profile is selected from a singularrelease profile or a sigmoidal release profile; and a reswell triggeringagent comprising a second water-soluble solid chemical where the secondtriggering composition has a sigmoidal release profile for releasing thesecond water-soluble solid chemical (active agent) from the triggeringcomposition; and where the first water-soluble chemical has a highercumulative release than the second water-soluble chemical after exposureto aqueous fluid and before about 100% release.

In some aspects, the SAP, the deswell triggering agent, and the reswelltriggering agent of the solubility-based chemistry grouping and theneutralization-based chemistry grouping can be used on their own, or inconjuction with the chemicals of the release-based chemistry grouping toachieve the swell-deswell-reswell behavior of the present invention.However, in general, the chemicals of the release-based chemistrygrouping cannot be utilized on their own to achieve theswell-deswell-reswell behavior of the present invention.

Thus, in some aspects of this invention, a SAP may be triggered todeswell and reswell by a change in the solubility of the triggeringagent chemicals. In some aspects of this invention, an absorbentcomposition may comprise a SAP having anionic functional groups; adeswell triggering agent comprising a first water-soluble chemicalcomprising cations X having an ionized valence of two or more; and areswell triggering agent comprising a second water-soluble chemicalcomprising anions Y, wherein the cations X of the first water-solublechemical are capable of complexing with the anions Y of the secondwater-soluble chemical to form a salt having a solubility productconstant Ksp<10⁻⁵. Without intending to be bound thereby, it ishypothesized that the ion exchange reaction between the deswelltriggering agent and the SAP may result in ionic crosslinking in the gelnetwork that triggers the SAP to deswell and release the absorbedliquid. The ion exchange reaction between the reswell triggering agentand the deswelled SAP may remove at least a portion of ioniccrosslinking so that the SAP can reswell and absorb additional liquid.

The first water-soluble chemical as described herein comprises cationshaving an ionized valence of two or more. Specific examples of the firstchemical include, for example, aluminum chloride, aluminum sulfate,barium chloride, calcium acetate, calcium chloride, calcium formate,magnesium acetate, magnesium chloride, magnesium formate, zinc acetate,zinc chloride, zinc formate, and zinc sulfate.

The water-soluble chemical of the reswell triggering agent as describedherein includes anions which are capable of forming an insoluble saltwith the cations of the deswell triggering agent. The anions may beselected from F⁻, HCO₃ ⁻, CO₃ ²⁻, PO₄ ³⁻, SO₄ ²⁻, oxalate, citrate,sulfide, and polyphosphate anions. Specific examples of this chemicalinclude, for example, sodium fluoride, sodium hydrogen carbonate, sodiumcarbonate, sodium citrate, sodium oxalate, sodium phosphate, sodiumpolyphosphate, sodium sulfide, sodium sulfate, or sodiumtripolyphosphate.

It is noted that the deswell and reswell triggering agents discussedabove are suitable for anionic SAPs. However, if cationic SAPs areutilized, the deswell and reswell triggering agents themselves may bedifferent, but the mechanism (i.e., solubility-based chemistry andneutralization-based chemistry) for selecting the triggerings agentswill remain the same.

The triggering agents as described herein may further comprise apolymeric coating material for achieving controlled release ofwater-soluble chemicals. Specific examples of the coating materialinclude, for example, poly(meth)acrylate copolymers, polyacrylatecopolymers, ethyl cellulose, sodium carboxymethylcellulose, celluloseacetate, polyethylene glycol, maleated polypropylene, polyolefincopolymers, or combinations thereof. In certain preferred aspects, thepolymeric coating used in the coatings of the present inventioncomprises copolymerizates of acrylic and methacrylic acid esters with alow content of quaternary ammonium groups. Such copolymerizates areoften referred to as ammonio methacrylate copolymers, and arecommercially available from Rohm Pharma AG, e.g., under the tradenameEUDRAGIT. In certain aspects, the polymeric coating used in the coatingsof the present invention comprises ethyl cellulose and/or celluloseacetate. In other aspects, the polymeric coating used in the coatings ofthe present invention may comprise maleated polypropylene

As noted above, in some aspects of the invention, the absorbentcomposition may include a deswell and reswell triggering agents having aselected release profile respectively for releasing the water-solublechemical after exposure to aqueous fluid wherein the first water-solublechemical has higher cumulative release than the second water-solublechemical before the first water-soluble chemical is 100% released. Therelease profile is selected from singular release profile or sigmoidalrelease profile.

In some aspects, the absorbent composition may include deswell andreswell triggering agents each having a release profile wherein fromabout 50 wt % to 100 wt % of the water-soluble solid chemical isreleased from the deswell or reswell triggering agent in less than about240 minutes after exposure to aqueous liquid, as measured by the releaseprofile measurement in Release Profile Test as set forth herein.

In another aspect, the absorbent composition may include a SAPcomprising partially neutralized crosslinked poly(acrylic acid), havingfrom about 40 to about 60 molar percent of the neutralized acidicfunctional groups, and a centrifuge retention capacity of at least about15 grams of 0.9% by weight sodium chloride solution per gram ofsuperabsorbent (g/g), or at least about 25 g/g, or at least about 30g/g, or from about 25 g/g to about 60 g/g, as set forth by theCentrifuge Retention Capacity Test set forth herein.

In another aspect, the absorbent composition may include a SAP that mayinclude from about 0.05 to about 10.0 wt % of a blowing agent. In someaspects, the blowing agent may be encapsulated by a resin that may beselected from natural or synthetic resins, acrylonitrile-butadienerubbers, viscous settable ceramic materials, polyolefins, polyethylenegylcol, olefin copolymers, polyaromatic olefins, styrenic compounds orpolymerized halo-diolefins. In other aspects, the absorbent compositionmay include a SAP that has a vortex time of 45 seconds or less asmeasured by the Vortex Test set forth herein. It has been discoveredthat the increase of absorption speed of the SAP described herein mayimprove the swelling and reswelling capacity in theswelling-deswelling-reswelling cycle.

As referenced above, in some aspects of this invention, it has beendiscovered that the mass efficiency and absorption capacity efficiencymay be improved by the decrease of degree of neutralization and decreaseof internal crosslinking of superabsorbent polymers. In another aspectof this invention, a SAP may have a degree of neutralization lower than70% degree of neutralization. In particular the absorbent compositioncomprises a SAP comprising partially neutralized crosslinkedpoly(acrylic acid) wherein from about 40 molar percent to about 60 molarpercent of the acidic functional groups are neutralized, and having a pHless than about 6.0, a deswell triggering agent that includes a firstwater-soluble chemical, and a reswell triggering agent having a pH ofabout 10 or more wherein the absorbent composition exhibits aswell-deswell-reswell behavior and the resultant swollen SAP has a pHhigher than the original SAP. In some aspects, the SAPs as describedherein can be made more sensitive to the triggering agents, for example,when the deswell triggering agent comprises an acid such as sulfamicacid (also known as amidosulfonic acid, amidosulfuric acid,aminosulfonic acid, and sulfamidic acid) or a water-soluble chemicalhaving multivalent cations such as Ca²⁺, and the reswell triggeringagent comprises a base or a basic material such as sodium carbonate.

One advantage of this invention is that a lesser percentage of thedeswell and reswell triggering agents with respect to a superabsorbentpolymer composition of the present invention can be utilized to achievethe same amount of deswelling liquid and reswelling capacity as comparedto a commercial superabsorbent polymer. In addition, the absorbentcomposition as described herein shows an increase of the swelling andreswelling capacities compared with the same absorbent composition, butcomprising a commercial superabsorbent polymer instead of asuperabsorbent polymer composition of the present invention.

In another aspect of this invention, the SAP and the deswell and reswelltriggering agents are in particle form, and the SAP particles and thedeswell and reswell triggering agent particles have a mean particle sizefrom about 150 μm to about 850 μm as measured by screening through aU.S. standard 20 mesh screen and retained on a U.S. standard 100 meshscreen.

In another aspect of this invention, at least one of said triggeringagents is spatially separated from said SAP.

In another aspect of this invention, at least one triggering agent has aprofile selected from a sigmoidal release profile or a singular releaseprofile.

As referenced above, in another aspect of this invention, the absorbentcomposition comprises a SAP comprising an optional blowing agent; adeswell triggering agent comprising a first water-soluble solid chemicalwherein the deswell triggering agent has a release profile for releasingthe water-soluble solid chemical from the triggering agent wherein therelease profile is selected from a singular release profile or asigmoidal release profile; and a reswell triggering agent comprising asecond water-soluble solid chemical wherein the reswell triggering agenthas a sigmoidal release profile for releasing the second water-solublesolid chemical from the triggering agent, wherein the firstwater-soluble chemical has higher cumulative release than the secondwater-soluble chemical after exposure to aqueous fluid and before about100% release.

In another aspect of this invention, an absorbent composition comprisesa SAP comprising partially neutralized crosslinked poly(acrylic acid)and having a first absorption capacity; a deswell triggering agent; anda reswell triggering agent, wherein the SAP and the deswell and reswelltriggering agents are in particle form, and the SAP particles and thedeswell and reswell triggering agent particles have a particle size offrom more than about 150 μm to less than about 1000 μm.

In another aspect of this invention, an absorbent composition comprisesa SAP; and a triggering agent comprising a water-soluble solid chemicalwherein the triggering agent has a release profile for releasing thewater-soluble solid chemical from the triggering agent, wherein therelease profile is selected from a singular release profile or asigmoidal release profile, wherein the SAP and the triggering agent arein particle form, and the SAP particles and the triggering agentparticles have a particle size of from more than about 150 μm to lessthan about 1000 μm.

The water-soluble solid chemical as described herein is selected fromsulfamic acid, citric acid, calcium formate, calcium chloride, calciumhydroxide, calcium oxide, calcium acetate, magnesium acetate, magnesiumchloride, magnesium formate, barium chloride, aluminum chloride,aluminum sulfate, sodium aluminate, zinc chloride, zinc acetate, zincformate, zinc sulfate, sodium fluoride, sodium hydrogen carbonate,sodium carbonate, sodium sulfate, sodium phosphate, sodiumpolyphosphate, sodium oxalate, sodium sulfide, or sodiumtripolyphosphate.

In another aspect of this invention, an absorbent material comprises aSAP; a deswell triggering agent comprising a first water-soluble solidchemical wherein the deswell triggering agent may have a release profilefor releasing the water-soluble solid chemical from the triggeringagent, wherein the release profile is selected from a singular releaseprofile or a sigmoidal release profile; and a reswell triggering agentcomprising a second water-soluble solid chemical wherein the reswelltriggering agent has a release profile for releasing the secondwater-soluble solid chemical from the triggering agent, wherein therelease profile is selected from a singular release profile or asigmoidal release profile; wherein the first water-soluble chemical hashigher cumulative release than the second water-soluble chemical afterexposure to aqueous fluid and before about 100% release.

An advantage of the absorbent composition of the present invention isthat the timing of the swelling-deswelling-reswelling cycle may becontrolled by adjusting such variables as the absorption rate of theSAP, the release rate of the deswell and reswell triggering agents, andthe mixing ratio of the SAP and triggering agents.

This invention further relates to triggering agents comprising awater-soluble solid chemical; and a polymeric coating material thatcoats the water soluble chemical in the amount of from about 0.1 wt % toabout 50 wt % of said water-soluble chemical, and wherein the triggeringagent has a singular or sigmoidal release profile for releasing thewater-soluble solid chemical from the triggering agent as measured bythe Release Profile Measurement Test and wherein the triggering agent isin particle form, and has a particle size of less than about 1000 μm.

In another aspect of this invention, the triggering agent comprises awater-soluble solid chemical selected from sulfamic acid, citric acid,aluminum chloride, aluminum sulfate, barium chloride, calcium acetate,calcium chloride, calcium formate, magnesium acetate, magnesiumchloride, magnesium formate, zinc acetate, zinc chloride, zinc formate,zinc sulfate, sodium fluoride, sodium hydrogen carbonate, sodiumcarbonate, sodium citrate, sodium oxalate, sodium phosphate, sodiumpolyphosphate, sodium sulfide, sodium sulfate, or sodiumtripolyphosphate, wherein the water-soluble solid chemical is coatedwith a polymeric coating selected from poly(meth)acrylate copolymers,polyacrylate copolymers, maleated polypropylene, ethyl cellulose, sodiumcarboxymethylcellulose, cellulose acetate, polyethylene glycol,polyolefin copolymers, or a combination thereof; and wherein thetriggering agent has a singular or sigmoidal release profile forreleasing the water-soluble solid chemical from the triggering agent asmeasured by the Release Profile Measurement Test and wherein thetriggering agent is in particle form, and has a particle size of frommore than about 150 μm to less than about 1000 μm.

Another aspect of this invention includes a triggering agent comprisinga) a water-soluble solid chemical; and b) a polymeric coating materialthat coats the water soluble chemical in the amount of from about 0.1 wt% to about 50 wt % of said water-soluble chemical; where the triggeringagent has a release profile for releasing the water-soluble solidchemical from the triggering agent after exposure to an aqueous solutionof the triggering agent, where the release profile is selected from asingular release profile or a sigmoidal release profile.

In another aspect of this invention, from about 50 wt % to 100 wt % ofthe water-soluble solid chemical is released from the triggering agentin less than about 240 minutes after the initial insult.

In another aspect of this invention, a triggering agent comprises awater-soluble solid chemical selected from sulfamic acid, calciumformate, sodium fluoride, sodium hydrogen carbonate, sodium carbonate,citric acid, calcium chloride, calcium hydroxide, calcium oxide,magnesium chloride, magnesium formate, barium chloride, aluminumsulfate, sodium aluminate, sodium sulfate, sodium phosphate, sodiumpolyphosphate, sodium oxalate, sodium sulfide, or sodiumtripolyphosphate; and the water-soluble solid chemical is coated with apolymeric coating selected from poly(meth)acrylate copolymers,polyacrylate copolymers, maleated polypropylene, ethyl cellulose, sodiumcarboxymethylcellulose, cellulose acetate, polyethylene glycol,polyolefin copolymers, or a combination thereof. In certain aspects, thepolymeric coating used in the coatings of the present inventioncomprises copolymerizates of acrylic and methacrylic acid esters with alow content of quaternary ammonium groups. Such copolymerizates areoften referred to as ammonio methacrylate copolymers, and arecommercially available from Rohm Pharma AG, e.g., under the tradenameEUDRAGIT. In certain aspects of the present invention, the acryliccoating is derived from a mixture of two acrylic resin lacquers used inthe form of aqueous dispersions, commercially available from Rohm Pharmaunder the Tradename EUDRAGIT RL 30 D and EUDRAGIT RS 30 D, respectively.EUDRAGIT RL 30 D and EUDRAGIT RS 30 D are copolymers of acrylic andmethacrylic esters with a low content of quaternary ammonium groups, themolar ratio of ammonium groups to the remaining neutral (meth)acrylicesters being 1:20 in EUDRAGIT RL 30 D and 1:40 in EUDRAGIT RS 30 D. Themean molecular weight is about 150,000.

Various aspects of the present invention include a triggering agent, ora form thereof such as a deswell triggering agent or a reswelltriggering agent, comprising a water-soluble solid chemical and apolymeric coating material that coats the water soluble chemical in theamount of from about 0.1 wt % to about 50 wt %, or amounts between thesetwo limits, of said water-soluble chemical, wherein the triggering agentmay have a release profile for releasing the water-soluble solidchemical from the triggering agent after an insult of an aqueoussolution of the triggering agent, wherein the release profile isselected from a singular release profile or a sigmoidal release profile.

This invention further relates to triggering agents having a selectedrelease profile for release of the active agent from the triggeringagents, and to a method for the preparation of such triggering agents.In one aspect, the release profile of the triggering agents can becontrolled by selecting appropriate coating polymers that are applied onthe surface of the water-soluble chemicals. In another aspect, therelease profile can be controlled by adjusting the coating process forapplying the coating polymers.

The triggering agent(s) according to the present invention may beprepared by various methods known to those skilled in the art ofpreparing coated controlled release compositions. The triggering agentmay be prepared continuously or discontinuously in laboratory or in alarge-scale industrial manner.

An aspect of a first method to prepare triggering agent(s) may includethe following steps:

-   a. providing the water-soluble solid chemical particles;-   b. placing the water-soluble chemical into a container;-   c. fluidizing the water-soluble solid chemical particles;-   d. spraying a polymeric coating onto the fluidized particles; and-   e. drying the coated particles, for example at about 50° C. for    about 2 days.

A second method to prepare triggering agents may include the followingsteps:

-   a. stirring the water-soluble solid chemical particles in a mixer;-   b. adding polymeric coating to the water-soluble solid chemical    particles; and-   c. heating the coated particles, for example at about 50° C. for    about 2 hours.

A third method to prepare triggering agents is a fluid bed process andmay include the following steps:

-   a. preparing a coating solution of the polymeric coating, talc, and    triethyl citrate;-   b. fluidizing water-soluble solid chemical particles;-   c. spraying the coating solution onto the water-soluble solid    chemical particles; and-   d. drying the coated particles, for example at about 40° C. for    about 24 hours.

A stabilized product of the triggering agent may be obtained bysubjecting the coated substrate to oven heating at a temperature abovethe glass transition temperature (Tg) of the plasticized acrylic polymerfor the required time period, the optimum values for temperature andtime for the particular formulation being determined experimentally.

The cured, coated compositions of the present invention provide a stabledissolution profile when stored for extended periods of time at roomtemperature and ambient humidity (e.g., long term (real time) testing),and when tested under accelerated storage conditions.

In some aspects, the triggering agents can be present in an absorbentcomposite or absorbent system as descrete particles (including otherforms, such as film, flakes, fibers, nanparticles and the like). Inother aspects, at least one of the triggering agents can be coated ontothe SAP, such as a superabsorbent polymer particle.

In some aspects, the SAP can be a superabsorbent polymer composition ofthe present invention. A superabsorbent polymer composition as set forthin aspects of the present invention is obtained by the initialpolymerization of from about 55% to about 99.9% by weight of thesuperabsorbent polymer composition of polymerizable unsaturated acidgroup containing monomer. A suitable monomer may include any of thosecontaining carboxyl groups, such as acrylic acid, methacrylic acid, or2-acrylamido-2-methylpropanesulfonic acid, or mixtures thereof. At leastabout 50% by weight, or at least about 75% by weight of the acid groupsmay be carboxyl groups.

The acid groups may be neutralized to the extent of at least about 25mol %, that is, the acid groups may be present as sodium, potassium, orammonium salts. In some aspects, the degree of neutralization may be atleast 40 mol % or at least about 50 mol %, such as at least 60 mol %, orat least 70 mol %, or from about 40 mol % to about 60 mol %. In someaspects, it is desirable to utilize polymers obtained by polymerizationof acrylic acid or methacrylic acid, the carboxyl groups of which areneutralized to the extent of from about 50 mol % to about 80 mol %, inthe presence of internal crosslinking agents.

In some aspects, the suitable monomer that may be copolymerized with theethylenically unsaturated monomer may include, but is not limited toacrylamide, methacrylamide, hydroxyethyl acrylate,dimethylaminoalkyl(meth)-acrylate, ethoxylated(meth)-acrylates,dimethylaminopropylacrylamide, or acrylamidopropyltrimethylammoniumchloride. Such monomer may be present in a range of from 0% to about 40%by weight of the copolymerized monomer.

The superabsorbent polymer composition of the invention may also includeinternal crosslinking agents. The internal crosslinking agent has atleast two ethylenically unsaturated double bonds, or one ethylenicallyunsaturated double bond and one functional group that is reactive towardacid groups of the polymerizable unsaturated acid group containingmonomer, or several functional groups that are reactive towards acidgroups may be used as the internal crosslinking component and isdesirably present during the polymerization of the polymerizableunsaturated acid group containing a monomer.

Examples of internal crosslinking agents include, but are not limitedto, aliphatic unsaturated amides, such as methylenebisacryl- or-methacrylamide or ethylenebisacrylamide; aliphatic esters of polyols oralkoxylated polyols with ethylenically unsaturated acids, such asdi(meth)acrylates or tri(meth)acrylates of butanediol or ethyleneglycol, polyglycols or trimethylolpropane; di- and triacrylate esters oftrimethylolpropane which may be oxyalkylated, desirably ethoxylated,with about 1 to about 30 mol of alkylene oxide; acrylate andmethacrylate esters of glycerol and pentaerythritol and of glycerol andpentaerythritol oxyethylated with desirably about 1 to about 30 mol ofethylene oxide; allyl compounds, such as allyl(meth)acrylate,alkoxylated allyl(meth)acrylate reacted with desirably about 1 to about30 mol of ethylene oxide, triallyl cyanurate, triallyl isocyanurate,maleic acid diallyl ester, poly-allyl esters, tetraallyloxyethane,triallylamine, tetraallylethylenediamine, diols, polyols, hydroxy allylor acrylate compounds and allyl esters of phosphoric acid or phosphorousacid; and monomers that are capable of crosslinking, such as N-methylolcompounds of unsaturated amides, such as of methacrylamide oracrylamide, and the ethers derived there from. Ionic crosslinkers suchas multivalent metal salts may also be employed. Mixtures of thecrosslinking agents mentioned may also be employed. The content of theinternal crosslinking agents is from about 0.001% to about 5% by weightsuch as from about 0.2% to about 3% by weight based on the total amountof the polymerizable unsaturated acid group containing monomer.

In another aspect of the present invention, from about 0.05 to about 10wt %, such as from about 0.2 wt % to about 5 wt %, from about 0.2 wt %to about 5 wt %, of a blowing agent (based on the total monomer solutionweight) may be added to the monomer solution. The blowing agents may beadded prior to, simultaneously with, or immediately after polymerizationis initiated. The blowing agents are not as effective if added after thehydrogel is formed, nor are they effective when added after chopping ordrying the gelled polymer. By varying the amount of the blowing agent,the release of the blowing agent may be timed to provide the mostadvantageous microcellular structure of the resulting hydrogel.

The blowing agents may include any carbonate or bicarbonate containingsalt, or mixed salt, sodium carbonate, potassium carbonate, ammoniumcarbonate, magnesium carbonate, or magnesium (hydrolytic) carbonates,calcium carbonate, barium carbonate, bicarbonates and hydrates of these,azo compounds or other cations, as well as naturally occurringcarbonates, such as dolomite, or mixtures thereof. Blowing agents mayinclude carbonate salts of multivalent cations, such as Mg²⁺, Ca²⁺,Zn²⁺, and the like. Although certain of the multivalent transition metalcations may be used, some of them, such as ferric cation, may causecolor staining and may be subject to reduction-oxidation reactions orhydrolysis equilibria in water. This may lead to difficulties in qualitycontrol of the final polymeric product. Also, other multivalent cations,such as Ni²⁺, Ba²⁺, Cd²⁺, and Hg²⁺, would be unacceptable because ofpotential toxic or skin sensitizing effects. A preferred blowing agentis MgCO₃, which may also be represented by the formula(MgCO₃)₄.Mg(OH)₂.5H₂O. Another preferred blowing agent is (NH₄)₂CO₃. Theblowing agents MgCO₃ and (NH₄)₂CO₃ may also be used in mixtures.

Such blowing agents may be resin encapsulated. Encapsulation of suchblowing agents provides a controllable delayed release of a gas such ascarbon dioxide when dispersed in a monomer solution that is heated orpolymerized in accordance with the present invention. The method forencapsulation comprises coating a particular blowing agent with a resinthat may be diluted in a solvent solution. The solvent utilized may bean organic or inorganic solvent such as water depending on the nature ofthe coating to be applied. A second coating, generally called a sealingcoating, may be applied on the encapsulated blowing agent.

Resins employed in encapsulating the blowing agent in the superabsorbentpolymers composition of the present invention may include but are notlimited to natural and synthetic resins, polyolefins (for example,polyethylene and polypropylene), olefin copolymers (for example,copolymers of ethylene and ethylvinylacetate), polyaromatic olefins,styrenic compounds and polymerized halo-diolefins (for example,neoprene, ethylene-propylene copolymers, polyvinyl chloride, polyvinylalcohol, polyvinyl acetate, polyacrylic acid derivatives, polycarbonate,polyesters, poly-alpha methylstyrene and polystyrene), starch, gelatin,and cellulose. Preferred resin materials include polyols such aspolyethylene glycol.

From 0 to about 95% by weight of the appropriate solvent may be added tothe resin to form a solution and coated on to the blowing agent. Resinsolution may be applied on the blowing agent in an amount from about 10%to about 80% by weight of the encapsulation compound, such as from about30% to about 70% by weight of the encapsulation compound, and may beapplied with any encapsulating method commonly employed in the artincluding, but not limited to, tumbling or spraying. The purpose of theencapsulating resin is to delay the gas release by the blowing agent inthe monomer solution until a later stage of the polymerization process,allowing control of and improving the microcellular structure of thehydrogel.

The encapsulation of the blowing agent by the resinous substrate may beaccomplished at room temperature, but elevated temperatures arepreferred. The resinous substrate may be from about 30% to about 70% byweight of the encapsulated compound.

The superabsorbent polymer composition of the invention may also includefrom about 50 ppm to about 1000 ppm of a thermal initiator based on thepolymerizable unsaturated acid group containing monomer. Thermalinitiators may include persulfates such as sodium persulfate, potassiumpersulfate, and ammonium persulfate; peroxides such as hydrogenperoxide, benzoyl peroxide, t-butyl peroxide, and methyl ethyl ketoneperoxide; peroxyesters such as t-butylperoxypivalate,t-amylperoxypivalate, t-amylperoxy-2-ethylhexanoate andt-butylperoxyisobutyrate; and azo compounds such as azonitrilecompounds, azoamidine compounds, cyclic azoamidine compounds, azoamidecompounds, alkylazo compounds,2,2′-azobis(2-amidinopropane)dihydrochloride, and2,2′-azobis(2-(2-imidazolin-2-yl)propane)dihydrochloride.

In some aspects, initiators may be used for initiation of thefree-radical polymerization. Suitable initiators may include, but arenot limited to, azo or peroxo compounds, redox systems or UV initiators,sensitizers, and/or radiation.

After polymerization, the superabsorbent polymer becomes a crosslinkedhydrogel that may be prepared into superabsorbent polymer particles. Thesuperabsorbent polymer particles may then be surface crosslinked by theaddition of a surface crosslinking agent and heat-treatment. In general,surface crosslinking is a process that is believed to increase thecrosslink density of the polymer matrix in the vicinity of thesuperabsorbent particle surface with respect to the crosslinking densityof the particle interior.

In some particular aspects, desirable surface crosslinking agentsinclude chemicals with one or more functional groups that are reactivetoward pendant groups of the polymer chains, typically the acid groups.The surface crosslinking agent may be present in an amount of from about0.001% to about 5% by weight of the dry superabsorbent polymercomposition, such as from about 0.1% to about 3% by weight, or such asfrom about 0.1% to about 1% by weight, based on the weight of the drysuperabsorbent polymer composition. Applicants have found that a heattreatment step after addition of the surface crosslinking agent isdesirable.

Surface crosslinking agents are chemical compounds that may containfunctional groups capable of reacting with carboxylic acid or carboxylgroups. Surface crosslinking agents may include two functional groupssuch as some alcohol, amine, aldehyde, and carbonate groups may be used.Crosslinker molecules having multiple different functions may also beemployed, such as polyols, polyamines, polyaminoalcohols, and alkylenecarbonates. Ethylene glycol, diethylene glycol, triethylene glycol,polyethylene glycol, glycerol, polyglycerol, propylene glycol,diethanolamine, triethanolamine, polypropylene glycol, block copolymersof ethylene oxide and propylene oxide, sorbitan fatty acid esters,ethoxylated sorbitan fatty acid esters, trimethylolpropane, ethoxylatedtrimethylolpropane, pentaerythritol, ethoxylated pentaerythritol,polyvinyl alcohol, sorbitol, ethylene carbonate, and propylene carbonatemay be used. Polyols and ethylene carbonate may be used as surfacecrosslinking agents.

Surface crosslinking agents may be an alkylene carbonate followed byheating to effect surface crosslinking, which may improve the surfacecrosslinking density and the gel strength characteristics of thesuperabsorbent polymer particle. More specifically, the surfacecrosslinking agent may be coated onto the superabsorbent polymerparticulate by mixing the polymer particulate with an aqueous alcoholicsolution of the alkylene carbonate surface crosslinking agent. Theamount of alcohol may be determined by the solubility of the alkylenecarbonate and is kept as low as possible for various reasons. Suitablealcohols are methanol, isopropanol, ethanol, butanol, or butyl glycol,as well as mixtures of these alcohols. In some aspects, the solventdesirably is water, which typically is used in an amount of about 0.3%by weight to about 5.0% by weight, based on the weight of the drysuperabsorbent polymer. In other aspects, the alkylene carbonate surfacecrosslinking agent may be dissolved in water without any alcohol. Instill other aspects, the alkylene carbonate surface crosslinking agentmay be applied from a powder mixture, for example, with an inorganiccarrier material, such as silicone dioxide (SiO₂), or in a vapor stateby sublimation of the alkylene carbonate.

To achieve the desired surface crosslinking properties, the alkylenecarbonate is distributed evenly on the particulate superabsorbentpolymer. For this purpose, mixing is effected in suitable mixers knownin the art, such as fluidized bed mixers, paddle mixers, rotary drummixers, or twin-worm mixers. It is also possible to carry out thecoating of the particulate superabsorbent polymer during one of theprocess steps in the production of the particulate superabsorbentpolymer. In one particular aspect, a suitable process for this purposeis the inverse suspension polymerization process.

The heat treatment, which may follow the coating treatment, may becarried out as follows. In general, the heat treatment is at atemperature of from about 100° C. to about 300° C. Lower temperaturesare possible if highly reactive epoxide crosslinking agents are used.However, if alkylene carbonates are used, then the thermal treatment issuitably at a temperature of from about 150° C. to about 250° C. In thisparticular aspect, the treatment temperature depends on the swell timeand the kind of alkylene carbonate. For example, at a temperature ofabout 150° C., the thermal treatment may be carried out for one hour orlonger. In contrast, at a temperature of about 250° C., a few minutes(e.g., from about 0.5 minutes to about 5 minutes) are sufficient toachieve the desired surface cross-linking properties. The thermaltreatment may be carried out in conventional dryers or ovens known inthe art.

The superabsorbent polymer composition of the present invention mayfurther include from 0 to about 5 wt % of a multivalent metal salt onthe surface of the polymer, based on the weight of the drysuperabsorbent polymer composition. The multivalent metal salt ispreferably water soluble. Examples of metal cations include the cationsof Al, Fe, Zr, Mg, and Zn. The metal cation may have a valence of atleast +3, such as with Al³⁺ being most preferred. Examples of anions inthe multivalent metal salt include halides, chlorohydrates, sulfates,lactate, nitrates, and acetates. Examples of such multivalent metalsalts include aluminum sulfate, and aluminum lactate. A form of aluminumsulfate is hydrated aluminum sulfate, preferably aluminum sulfate havingfrom 12 to 14 waters of hydration. Mixtures of multivalent metal saltsmay be employed.

The polymer and multivalent metal salt suitably may be mixed by dryblending, or in solution such as an aqueous solution, using means wellknown to those skilled in the art. With dry blending, a binder may beemployed in an amount which is sufficient to ensure that a substantiallyuniform mixture of the salt and the superabsorbent polymer ismaintained. The binder may be water or a nonvolatile organic compoundhaving a boiling point of at least 150° C. Examples of binders includewater, polyols such as propylene glycol, glycerin, and poly(ethyleneglycol).

In some aspects, the superabsorbent polymer composition of the presentinvention may include up to about 5% by weight, and from about 0.001% toabout 5% by weight, and from about 0.01% to about 0.5% by weight of thedry superabsorbent polymer composition of a polymeric coating, such as athermoplastic coating, or a cationic coating, or a combination of athermoplastic coating and a cationic coating. In some particularaspects, the polymeric coating may be a polymer that may be a solid,emulsion, suspension, colloidal, or solubilized state, or combinationsthereof. Polymeric coatings suitable for this invention may include, butare not limited to, a thermoplastic coating having a thermoplastic melttemperature, wherein the polymeric coating may be applied to theparticle surface coincident with, or followed by a temperature of thetreated superabsorbent polymer particle at about the thermoplastic melttemperature.

Examples of thermoplastic polymers that may also be employed include,but are not limited to, polyolefin, polyethylene, polyester, polyamide,polyurethane, styrene polybutadiene, linear low density polyethylene(LLDPE), ethylene acrylic acid copolymer (EAA), ethylene alkylmethacrylate copolymer (EMA), polypropylene (PP), maleatedpolypropylene, ethylene vinyl acetate copolymer (EVA), polyester,polyamide, and blends of all families of polyolefins, such as blends ofPP, EVA, EMA, EEA, EBA, HDPE, MDPE, LDPE, LLDPE, and/or VLDPE. Athermoplastic polymer may be functionalized to have additional benefitssuch as water solubility or dispersability.

Polymeric coatings of this invention may also include a cationicpolymer. A cationic polymer as used herein refers to a polymer ormixture of polymers comprising a functional group, or groups, having apotential of becoming positively charged ions upon ionization in anaqueous solution. Suitable functional groups for a cationic polymerinclude, but are not limited to, primary, secondary, or tertiary aminogroups, imino groups, imido groups, amido groups, and quaternaryammonium groups. Examples of synthetic cationic polymers include, butare not limited to, the salts or partial salts of poly(vinyl amines),poly(allylamines), poly(ethylene imine), poly(amino propanol vinylethers), poly(acrylamidopropyl trimethyl ammonium chloride), andpoly(diallyldimethyl ammonium chloride). Poly(vinyl amines) include, butare not limited to, LUPAMIN 9095 available from BASF Corporation, MountOlive, N.J. Examples of natural-based cationic polymers include, but arenot limited to, partially deacetylated chitin, chitosan, and chitosansalts. Synthetic polypeptides such as polyasparagins, polylysines,polyglutamines, and polyarginines are also suitable cationic polymers.

The superabsorbent polymer compositions according to the invention mayinclude from 0 to about 5 wt %, or from 0.05 to about 2.0 wt %, of amultivalent metal salt, based on the dry superabsorbent polymercomposition. The multivalent metal salt may be applied to the surface ofthe superabsorbent polymer composition. The multivalent metal salt maybe water soluble. Examples of metal cations include the cations of Al,Fe, Zr, Mg, and Zn. The metal cation may have a valence of at least +3,with Al being most preferred. Examples of anions in the multivalentmetal salt include halides, chlorohydrates, sulfates, lactates, nitratesand acetates, with chlorides, sulfates, chlorohydrates, and acetatesbeing preferred, chlorohydrates and sulfates being more preferred, andsulfates being the most preferred. Aluminum sulfate is the mostpreferred multivalent metal salt and is readily commercially available.The multivalent metal salt may be an aluminum sulfate such as hydratedaluminum sulfate, such as aluminum sulfate having from 12 to 14 watersof hydration. The multivalent metal salt may be aluminum lactate.Mixtures of multivalent metal salts may be employed.

The superabsorbent polymer compositions according to the invention mayinclude from about 0.01% to about 2% by weight or from about 0.01% toabout 1% by weight based on the dry superabsorbent polymer compositionof a water-insoluble inorganic metal compound. The water-insolubleinorganic metal compound may be applied to the surface of thesuperabsorbent polymer composition. The water-insoluble inorganic metalcompounds may include, but are not limited to, a cation selected fromaluminum, titanium, calcium, or iron and an anion selected fromphosphate, borate, or chromate. Examples of water-insoluble inorganicmetal compounds include aluminum phosphate and an insoluble metalborate. The insoluble metal borate may be selected from titanium borate,aluminum borate, iron borate, magnesium borate, manganese borate, orcalcium borate. The chemical formula TiBO will be used herein todesignate titanium borate and analogous compounds such as titanium (III)borate TiBO₃. In addition, the chemical formulation also designates thecase when titanium (III) borate TiBO₃ is treated with hydrogen peroxideto obtain titanium (IV) borate. The inorganic metal compound may have amass median particle size of less than about 2 μm, and may have a massmedian particle size of less than about 1 μm.

The inorganic metal compound may be applied in the dry physical form tothe surface of the superabsorbent polymer particles. For this, thesuperabsorbent polymer particles may be intimately mixed with the finelydivided inorganic metal compound. The finely divided inorganic metalcompound may be added at about room temperature to the superabsorbentpolymer composition particles and mixed in until an about homogeneousmixture is present. For this purpose, mixing is effected in suitablemixers known in the art, such as fluidized bed mixers, paddle mixers,rotary drum mixers, or twin-worm mixers. The mixing of thesuperabsorbent polymer particles with the finely divided water-insolubleinorganic metal compound may take place before or after any surfacecrosslinking, for example during the application of the surfacecrosslinking agent.

Alternatively, a suspension of a finely divided water-insolubleinorganic metal compounds may be prepared and applied to a particulatewater absorbent polymer. The suspension may be applied, for example, byspraying. Useful dispersion media for preparing the suspension includewater, organic solvents such as alcohols, for example methanol, ethanol,isopropanol, ketones, for example acetone, methyl ethyl ketone, ormixtures of water with the aforementioned organic solvents. Other usefuldispersion media include dispersion aids, surfactants, protectivecolloidals, viscosity modifiers, and other auxiliaries to assist in thepreparation of the suspension. The suspension may be applied inconventional reaction mixers, or mixing and drying systems as describedabove at a temperature in the range from room temperature to less thanthe boiling point of the dispersion medium, or at about roomtemperature. It is appropriate to combine the application of thesuspension with a surface crosslinking step by dispersing the finelydivided water-insoluble metal salt in the solution of the surfacecrosslinking agent. Alternatively, the suspension may also be appliedbefore or after the surface crosslinking step. The application of theslurry may be followed by a drying step.

In some aspects, the superabsorbent polymer compositions according tothe invention may also include from 0% to about 5%, or in thealternative from about 0.01% to about 3%, by weight of the drysuperabsorbent polymer composition of silica. Examples of silica includefumed silica, precipitated silica, silicon dioxide, silicic acid, andsilicates. In some particular aspects, microscopic noncrystallinesilicon dioxide may be desirable. Products include SIPERNAT 22S andAEROSIL 200 available from Degussa Corporation, Parsippany, N.J. In someaspects, the particle diameter of the inorganic powder may be 1,000 μmor smaller, such as 100 μm or smaller.

In some aspects, the superabsorbent polymer compositions may alsoinclude from 0% to about 30% by weight of the dry superabsorbent polymercomposition, such as from about 0.1% to about 5% by weight, ofwater-soluble polymers based on the weight of the dry superabsorbentpolymer composition, of partly or completely hydrolyzed polyvinylacetate, polyvinylpyrrolidone, starch or starch derivatives,polyglycols, polyethylene oxides, polypropylene oxides, or polyacrylicacids.

In some aspects, additional surface additives may optionally be employedwith the superabsorbent polymer particles, such as odor-bindingsubstances, such as cyclodextrins, zeolites, inorganic or organic salts,and similar materials, anti-caking additives, flow modification agents,surfactants, viscosity modifiers, and the like. In addition, surfaceadditives may be employed that perform several roles during surfacemodifications. For example, a single additive may be a surfactant,viscosity modifier, and may react to crosslink polymer chains.

In some aspects, the superabsorbent polymer compositions of the presentinvention may, after a heat treatment step, be treated with water sothat the superabsorbent polymer composition has water content of up toabout 10% by weight of the superabsorbent polymer composition. Thiswater may be added with one or more of the surface additives from aboveadded to the superabsorbent polymer.

In some aspects, the superabsorbent polymer compositions according tothe invention may be prepared by two methods. In some aspects, thecomposition may be prepared continuously or discontinuously in alarge-scale industrial manner, the after-crosslinking according to theinvention being carried out accordingly.

According to one method, the partially neutralized monomer, such asacrylic acid, may be converted into a gel by free-radical polymerizationin aqueous solution in the presence of crosslinking agents and anyfurther components, and the gel may be comminuted, dried, ground, andsieved off to the desired particle size. For the present invention, thesize of the high-capacity superabsorbent polymer composition particlesis dependent on manufacturing processes including milling and sieving.It is well known to those skilled in the art that particle sizedistribution of the superabsorbent polymer particles resembles a normaldistribution or a bell shaped curve. It is also known that for variousreasons, the normal distribution of the particle size distribution maybe skewed in either direction.

The superabsorbent polymer particles of the present invention generallyinclude particle sizes ranging from about 50 to about 1000 μm, or fromabout 150 to about 850 μm. The present invention may include at leastabout 40 wt % of the particles having a particle size from about 300 μmto about 600 μm, at least about 50 wt % of the particles having aparticle size from about 300 μm to about 600 μm, or at least about 60 wt% of the particles having a particle size from about 300 μm to about 600μm as measured by screening through a U.S. standard 30 mesh screen andretained on a U.S. standard 50 mesh screen. In addition, the sizedistribution of the superabsorbent polymer particles of the presentinvention may include less than about 30% by weight of particles havinga size greater than about 600 microns, and less than about 30% by weightof particles having a size of less than about 300 microns as measuredusing for example a RO-TAP Mechanical Sieve Shaker Model B availablefrom W. S. Tyler, Inc., Mentor, Ohio.

While the form of particles may be used by way of example of thephysical form of superabsorbent polymer composition, the invention isnot limited to this form and is applicable to other forms such asfibers, foams, films, beads, rods, and the like, as discussed above. Insome aspects, when the superabsorbent polymer composition exists asparticles or in granule form, it is desirable that these particles havea size of from about 150 μm to about 850 μm based on the sieving processthat is well known in the superabsorbent industry.

According to another method, inverse suspension and emulsionpolymerization may also be used for preparation of the productsaccording to the invention. According to these processes, an aqueous,partly neutralized solution of monomer, such as acrylic acid, may bedispersed in a hydrophobic, organic solvent with the aid of protectivecolloids and/or emulsifiers, and the polymerization is started by freeradical initiators. The internal crosslinking agents may be eitherdissolved in the monomer solution and are metered in together with this,or are added separately and optionally during the polymerization. Theaddition of a water-soluble polymer as the graft base optionally takesplace via the monomer solution or by direct introduction into theorganic solvent. The water is then removed azeotropically from themixture, and the polymer is filtered off and optionally dried. Internalcrosslinking may be carried out by polymerizing-in a polyfunctionalcrosslinking agent dissolved in the monomer solution and/or by reactionof suitable crosslinking agents with functional groups of the polymerduring the polymerization steps.

The superabsorbent polymer compositions of the present invention mayhave a vortex time as measured by the test procedure set forth herein,of about 45 seconds or less, or a vortex time of from about 45 secondsto about 5 seconds, or from about 40 seconds to about 10 seconds, orfrom about 35 seconds to about 15 seconds. In addition thesuperabsorbent polymer compositions may have a Centrifuge RetentionCapacity (CRC) as measured by the CRC Test of from about 15 g/g to about60 g/g, or about 20 g/g or more, or from about 20 g/g to about 60 g/g,or about 25 g/g or more, or from about 25 g/g to about 60 g/g.

The result of these methods is a superabsorbent pre-product. Asuperabsorbent pre-product as used herein is produced by repeating allof the steps for making the superabsorbent, up to and including dryingthe material, and coarse grinding in a crusher, and removing particlesgreater than about 850 μm and smaller than about 150 μm.

As referenced above, the absorbent composite or absorbent system of thepresent invention can have particular configurations of structure toprovide improved benefits. For example, in some aspects, referring toFIG. 5, there is presented a cross-section view of an absorbentcomposite 810 having an X-direction 97 and a Z-direction 99 comprisingSAP 812, a deswell triggering agent 814 and a reswell triggering agent816 located throughout (e.g., uniformly throughout) the absorbentcomposite 810.

Referring to FIG. 6, in some aspects, the absorbent composite 810 cancomprise a region having predominantly SAP 812 (hereinafter referred toas a SAP-rich region) 820 and a region having predominantly deswelland/or reswell triggering agent 814,816 (hereinafter referred to asTA-rich region) 822, where the regions are configured in theZ-direction.

Referring to FIG. 7, in some aspects, the absorbent composite 810 cancomprise a target zone 830. In some aspects, the absorbent composite 810can include SAP 812 uniformly distributed throughout the composite, withdeswell and/or reswell triggering agents 814,816 respectively, locatedsubstantially only in a target zone 830 and with the perimeter region832 comprising substantially only SAP 812.

The absorbent composition of the present invention may be comprised byan absorbent composite. Referring to FIG. 8A, in some aspects, theabsorbent composite 810 can comprise SAP 812 uniformly distributed in atleast a middle region 844 of the absorbent composite 810, and a deswelltriggering agent 814 and/or a reswell triggering agent 816 locatedsubstantially only in at least an upper region 842 or lower region 843of the absorbent composite 810. Referring to FIG. 8B, in furtheraspects, the deswell and/or reswell triggering agent 814,816 can besubstantially located in a target zone 830 of at least one of an upperregion 842 or lower region 843 and SAP can be located at least in amiddle region 844. In particular features, the SAP and triggering agentsare present in the regions 842,843,844 in uniform or variable basisweights. In other particular features, the triggering agents can bepresent in a target zone 830 of the regions 842,843 in uniform orvariable basis weights. Referring to FIG. 8C, in further aspects, adeswell triggering agent 814 can be located substantially only in anupper region 842 of the absorbent composite 810 and/or a reswelltriggering agent 816 can be located substantially only in a lower region843 of the absorbent composite 810, and the SAP can be located at leastin a middle region 844 of the absorbent composite 810. Referring to FIG.8D, in other particular features, the triggering agents 814,816 are eachpresent in a target zone 830 of an upper region 842 or lower region 843and SAP is located at least in a middle region 844. Referring to FIG.8E, in further aspects, a reswell triggering agent 816 can be locatedsubstantially only in an upper region 842 of the absorbent composite 810and/or a deswell triggering agent 814 can be located substantially onlyin a lower region 843 of the absorbent composite 810, and SAP can belocated at least in a middle region 844 of the absorbent composite 810.

Referring to FIG. 8F, in other particular features, the triggeringagents 814,816 are each present in a target zone 830 of an upper region842 or lower region 843, with SAP located at least in a middle region844. Referring to FIG. 8G, in other particular features, a reswelltriggering agent 816 is located in the middle region 844, a deswelltriggering agent 814 is located in an upper region 842, and SAP 812 islocated in a lower region 843 of the absorbent composite 810. Referringto FIG. 8H, in other particular features, a deswell triggering agent 814is located in the middle region 844, a reswell triggering agent 816 islocated in the upper region 842, and SAP is located in the lower regionof the absorbent composite 810. Referring to FIG. 8I, in otherparticular features, a reswell triggering agent 816 is located in themiddle region 844, SAP 812 is located in an upper region 842, anddeswell triggering agent 814 is located in a lower region 843 of theabsorbent composite 810. Referring to FIG. 8J, in other particularfeatures, a deswell triggering agent 814 is located in middle region844, SAP 812 is located in an upper region 842, and a reswell triggeringagent 716 is located in a lower region 843 of the absorbent composite810.

The absorbent composition of the present invention may also be comprisedby an absorbent system. Referring to FIG. 25A, in some aspects, theabsorbent system 700 can comprise SAP 712 uniformly distributedthroughout the absorbent composite layer 710, and a deswell and/orreswell triggering agent 714,716 located substantially only in at leastone discrete layer 742,743 located above and/or below the absorbentcomposite layer 710. Referring to FIG. 25B, in further aspects, thedeswell and/or reswell triggering agent 714,716 can be substantiallylocated in a target zone 730 of at least one discrete layer 742,743. Inparticular features, the triggering agents are present in the discretelayers in uniform or variable basis weights. In other particularfeatures, the triggering agents are present in a target zone 730 of thediscrete layers in uniform or variable basis weights. Referring to FIG.25C, in further aspects, a deswell triggering agent 714 can be locatedin a discrete layer 742 located above the absorbent composite layer 710and/or a reswell triggering agent 716 can be located substantially in adiscrete layer 743 located below the absorbent composite layer 710.Referring to FIG. 25D, in other particular features, the triggeringagents are each present in a target zone 730 of a discrete layer742,743. Referring to FIG. 25E, in further aspects, a reswell triggeringagent 716 can be located in a discrete layer 742 located above theabsorbent composite layer 710 and/or a deswell triggering agent 714 canbe located substantially in a discrete layer 743 located below theabsorbent composite layer 710.

Referring to FIG. 25F, in other particular features, the triggeringagents 714,716 are each present in a target zone 730 of a discrete layer742,743. Referring to FIG. 25G, in other particular features, a reswelltriggering agent 716 is located in the absorbent composite layer 710, adeswell triggering agent 714 is located in a discrete layer 742 abovethe absorbent composite layer 710, and SAP 712 is located in a discretelayer 743 below the absorbent composite layer 710. Referring to FIG.25H, in other particular features, SAP 712 is located in the absorbentcomposite layer 710, a deswell triggering agent 714 is located in adiscrete layer 742 above the absorbent composite layer 710, and areswell triggering agent 716 is located in an additional layer 748located above the deswell triggering agent layer 742. Referring to FIG.25I, in other particular features, a reswell triggering agent 716 islocated in the absorbent composite layer 710, SAP 712 is located in adiscrete layer 742 above the absorbent composite layer 710, and deswelltriggering agent 714 is located in a discrete layer 743 below theabsorbent composite layer 710. Referring to FIG. 25J, in otherparticular features, a SAP 712 is located in the absorbent compositelayer 710, deswell triggering agent 714 is located in a discrete layer743 below the absorbent composite layer 710, and a reswell triggeringagent 716 is located in an additional layer 746 below the reswelltriggering agen layer 743.

In still other aspects, the triggering agents could be located inadditional layers, such as surge layers, adhesive layers, tissue layers,foam layers, adhesive/tissue laminates, and the like of the absorbentsystems.

The distribution of the SAP and the triggering agents within theabsorbent composite or absorbent system can be determined by severalmethods. For example, image analysis such as SEM, x-ray imaging can beused. Additionally, solvent extraction followed by image analysismethods. The solvent extraction should be conducted in a manner thatonly the triggering agent will be dissolved in the solvent media. Forexample, a mixture of alcohol and water can be used to limit theswelling of the SAP but at the same time dissolving the triggeringagent.

It is understood that the various structural aspects presented above areprovided as examples only, and that numerous additional variations arealso contemplated without departing from the scope of the invention. Inother particular features, the triggering agents are present in a targetzone of the additional layers in desirable basis weights.

The present invention may be better understood with reference to thefollowing examples.

EXAMPLES

The present invention may be better understood with reference to thefigures and the following examples. The following examples and SAPs forthe examples are provided to illustrate the invention and do not limitthe scope of the claims. Unless otherwise stated, all parts andpercentages are by weight.

Superabsorbent Polymer Compositions

Preproduct B

Into a polyethylene container equipped with an agitator and coolingcoils was added 1167 grams of 50% NaOH and 2032 grams of distilled waterand cooled to 20° C. 500 grams of glacial acrylic acid was then added tothe caustic solution and the solution again cooled to 20° C. 3.75 gramsof polyethylene glycol monoallylether acrylate, 3.75 grams ofethoxylated trimethylol propane triacrylate SARTOMER 454 product, and1000 grams of glacial acrylic acid were added to the first solution,followed by cooling to 4-6° C. Nitrogen was bubbled through the monomersolution for about 10 minutes. The cooling coils were removed from thecontainer. Immediately prior to the addition of initiators, 47 g of thecoated FMC grade 50 sodium carbonate was added to the monomer solutionas a blowing agent (The coated blowing agent was prepared by spraying 9grams of polyethylene glycol 8000 solution (16.5 wt % in water) onto 300grams of sodium carbonate powder. The coated powder was relaxed at roomtemperature for at least 1 hour before it was used in the polymerizationbatch). To the monomer solution was added 50 g of 1% by weight of H₂O₂aqueous solution, 150 g of 2 wt % aqueous sodium persulfate solution,and 45 g of 0.5 wt % aqueous sodium erythorbate solution to initiatepolymerization reaction. The agitator was stopped and the initiatedmonomer was allowed to polymerize for 20 minutes. The resulting hydrogelwas chopped and extruded with a Hobart 4M6 commercial extruder, followedby drying in a Procter & Schwartz Model 062 forced air oven at 175° C.for 10 minutes with up flow and 6 minutes with down flow air on a 20in×40 in perforated metal tray to a final product moisture level of lessthan 5 wt %. The dried material was coarse-ground in a Prodeva Model315-S crusher, milled in an MPI 666-F three-stage roller mill and sievedwith a Minox MTS 600DS3V to remove particles greater than 850 μm andsmaller than 150 μm. The product had a CRC of 38 g/g and a vortex timeof 32 seconds.

Preproduct C

Into a polyethylene container equipped with an agitator and coolingcoils was added 1333 grams of 50% NaOH and 3988 grams of distilled waterand cooled to 20° C. 800 grams of glacial acrylic acid was then added tothe caustic solution and the solution again cooled to 20° C. 3.6 gramsof polyethylene glycol monoallylether acrylate, 3.6 grams of ethoxylatedtrimethylol propane triacrylate SARTOMER 454 product, and 1600 grams ofglacial acrylic acid were added to the first solution, followed bycooling to 4-6° C. Nitrogen was bubbled through the monomer solution forabout 10 minutes. The cooling coils were removed from the container. Tothe monomer solution was added 80 g of 1% by weight of H₂O₂ aqueoussolution, 120 g of 2 wt % aqueous sodium persulfate solution, and 72 gof 0.5 wt % aqueous sodium erythorbate solution to initiatepolymerization reaction. The agitator was stopped and the initiatedmonomer was allowed to polymerize for 20 minutes. The resulting hydrogelwas chopped and extruded with a Hobart 4M6 commercial extruder, followedby drying in a Procter & Schwartz Model 062 forced air oven at 175° C.for 10 minutes with up flow and 6 minutes with down flow air on a 20in×40 in perforated metal tray to a final product moisture level of lessthan 5 wt %. The dried material was coarse-ground in a Prodeva Model315-S crusher, milled in an MPI 666-F three-stage roller mill and sievedwith a Minox MTS 600DS3V to remove particles greater than 850 μm andsmaller than 150 μm. The product had a CRC of 36.2 g/g and a vortex timeof 60 seconds.

Preproduct D

Into a polyethylene container equipped with an agitator and coolingcoils was added 972 grams of 50% NaOH and 1,976 grams of distilled waterand cooled to 20° C. 583 grams of glacial acrylic acid was then added tothe caustic solution and the solution again cooled to 20° C. 2.625 gramsof polyethylene glycol monoallylether acrylate, 2.625 grams ofethoxylated trimethylol propane triacrylate SARTOMER 454 product, and1,167 grams of glacial acrylic acid were added to the first solution,followed by cooling to 4-6° C. Nitrogen was bubbled through the monomersolution for about 10 minutes. The cooling coils were removed from thecontainer. Immediately prior to the addition of initiators, 51.8 g ofthe coated FMC grade 50 sodium carbonate was added to the monomersolution as a blowing agent (The coated blowing agent was prepared byspraying 9 grams of polyethylene glycol 8000 solution (16.5 wt % inwater) onto 300 grams of sodium carbonate powder. The coated powder wasrelaxed at room temperature for at least 1 hour before it was used inthe polymerization batch). To the monomer solution was added 50 g of 1%by weight of H₂O₂ aqueous solution, 150 g of 2 wt % aqueous sodiumpersulfate solution, and 45 g of 0.5 wt % aqueous sodium erythorbatesolution to initiate polymerization reaction. The agitator was stoppedand the initiated monomer was allowed to polymerize for 20 minutes. Theresulting hydrogel was chopped and extruded with a Hobart 4M6 commercialextruder, followed by drying in a Procter & Schwartz Model 062 forcedair oven at 175° C. for 10 minutes with up flow and 6 minutes with downflow air on a 20 in×40 in perforated metal tray to a final productmoisture level of less than 5 wt %. The dried material was coarse-groundin a Prodeva Model 315-S crusher, milled in an MPI 666-F three-stageroller mill and sieved with a Minox MTS 600DS3V to remove particlesgreater than 850 μm and smaller than 150 μm. The product had a CRC of34.1 g/g and a vortex time of 29 seconds.

Preproduct E

Preproduct E is produced using the method of making Preproduct C exceptthat the amount of 50% NaOH, polyethylene glycol monoallyletheracrylate, and ethoxylated trimethylol propane triacrylate was changed to1066 grams, 2.4 grams, and 2.4 grams, respectively. The product had aCRC of 34.1 g/g and vortex time of 70 seconds.

Preproduct F

Preproduct F was produced following the same method as Preproduct D,except that the amount of polyethylene glycol monoallylether acrylate,and ethoxylated trimethylol propane triacrylate was changed 1.75 grams,and 1.75 grams, respectively. The product had a CRC of 40.1 g/g andvortex time of 26.3 seconds.

Superabsorbent Polymer Composition A (SAP-A)

SAP-A is a commercially available superabsorbent product FAVOR SXM-9300,manufactured by Evonik Stockhausen Inc., Greensboro, N.C. It has adegree of neutralization from about 65% to about 75%.

Superabsorbent Polymer Composition B (SAP-B)

Preproduct B was coated with 0.5% of SIPERNAT 22s, 1 wt % ethylenecarbonate, and 3 wt % water using a 25 wt % aqueous solution. The coatedPreproduct B was then heated in a convection oven at 185° C. for 45minutes. The surface crosslinked particulate material was then posttreated with 1000 ppm polyethylene glycol 8000 (polyethylene glycol withaverage molecular weight of 8000) and 5% water.

Superabsorbent Polymer Composition C (SAP-C)

Preproduct C was coated with 0.5% of SIPERNAT 22s, 1 wt % ethylenecarbonate and 3 wt % water using a 25 wt % aqueous solution. The coatedPreproduct C was then heated in a convection oven at 150° C. for 40minutes. The surface crosslinked particulate material was then posttreated with 500 ppm polyethylene glycol 8000 (polyethylene glycol withaverage molecular weight of 8000) and 2% water.

Superabsorbent Polymer Composition D (SAP-D)

Preproduct D was coated with 0.5% of SIPERNAT 22s, 1 wt % ethylenecarbonate and 3 wt % water using a 25 wt % aqueous solution. The coatedPreproduct D was then heated in a convection oven at 165° C. for 40minutes. The surface crosslinked particulate material was then posttreated with 500 ppm polyethylene glycol 8000 (polyethylene glycol withaverage molecular weight of 8000) and 2% water.

Superabsorbent Polymer Composition E (SAP-E)

Preproduct E was coated with 0.5% of SIPERNAT 22s, 1 wt % ethylenecarbonate and 3 wt % water using a 25 wt % aqueous solution. The coatedPreproduct E was then heated in a convection oven at 150° C. for 40minutes. The surface crosslinked particulate material was then posttreated with 500 ppm polyethylene glycol 8000 (polyethylene glycol withaverage molecular weight of 8000) and 2% water.

Superabsorbent Polymer Composition F (SAP-F)

Preproduct F was coated with 0.5% of SIPERNAT 22s, 1 wt % ethylenecarbonate and 3 wt % water using a 20 wt % aqueous solution. The coatedPreproduct F was then heated in a convection oven at 155° C. for 40minutes. The surface crosslinked particulate material was then posttreated with 1000 ppm polyethylene glycol 8000 (polyethylene glycol withaverage molecular weight of 8000) and 5% water.

The foregoing superabsorbent polymer compositions have the properties asshown in the following Table A.

TABLE A Properties of Superabsorbent Polymer Compositions Degree orCentrifuge Retention Vortex neutralization SAP Capacity (g/g) Time (min)(%) pH SXM9300 29.5 86 SAP-B 29.4 25 70 6.0 SAP-C 30 67 50 5.2 SAP-D29.4 31 50 5.3 SAP-E 29.1 65 40 4.9 SAP-F 33 41 50 5.3Examples of Triggering Agents

TABLE B Triggering agents Triggering Water-soluble Release agentchemical Coating Polymer profile TA_(D) - A sulfamic acid 5% EUDRAGIT RS30D sigmoidal TA_(D) - B sulfamic acid 10% EUDRAGIT RS 30D sigmoidalTA_(D) - C Calcium Formate 5% EUDRAGIT RS 30D singular TA_(D) - DCalcium Formate 10% EUDRAGIT RS 30D singular TA_(D) - E Calcium Formate2.25% Cellulose Acetate singular TA_(D) - F Calcium Formate 3% CelluloseAcetate and singular 3.5% ethyl cellulose TA_(D) - G Calcium Formate0.1% sodium carboxymethylcellulose TA_(R) - A Sodium 5% EUDRAGIT RS 30Dsigmoidal Carbonate TA_(R) - B Sodium 10% EUDRAGIT RS 30D sigmoidalCarbonate TA_(R) - C Sodium 18% EUDRAGIT RS 30D sigmoidal CarbonateTA_(R) - D Sodium 27% EUDRAGIT RS 30D sigmoidal Carbonate TA_(R) - ESodium 2% Maleated propylene singular Carbonate TA_(R) - F Sodium 6%Maleated propylene singular Carbonate

The abbreviations SAP-A, SAP-B, SAP-C, SAP-D, SAP-E, SAP-F, TA_(D)-A,TA_(D)-B, TA_(D)-C, TA_(D)-D, TA_(D)-E, TA_(D)-F, TA_(D)-G, TA_(R)-A,TA_(R)-B, TA_(R)-C, TC-D, TA_(R)-E, and TA_(R)-F from Tables A and B maybe used in the following examples.

Example 1 Preparation of poly(meth)acrylate Coated Sulfamic Acid(TA_(D)-A and TA_(D)-B)

A polymer solution or dispersion was sprayed on the surface ofwater-soluble solid chemicals to form a coating layer. Well suited forthis purpose are aqueous poly(meth)acrylate dispersions, for example,EUDRAGIT RS 30D, which is commercially available from Evonik PharmaPolymers.

The coating polymer dispersion was prepared according to the followingformulation:

EUDRAGIT RS 30D (30% aqueous dispersion) 1200 g Triethyl citrate  36 gTalc  180 g Water 1464 g

The mixture of coating materials was stirred in a container using anoverhead stirrer. The mixture was stirred for at least 15 minutes toensure good mixing before it was used to coat the water-soluble solidchemical.

About 800 g of sulfamic acid particles (particle size between 100-20mesh, U.S. Sieve Series) obtained from Sigma-Aldrich Company were placedin a Glatt WSG 5 fluidized bed apparatus. The Glatt unit was set up toprovide top spray by insertion of a top spray insert and a 150 micronfilter bag was utilized. The air used to fluidize the sulfamic acidparticles was conditioned to remove water vapor in the air. The coatingmaterial was applied at a coating material temperature of about 25° C.,an atomizing air pressure of 2.0 bar, and a spray flow rate of 8g/min/Kg. After the coating material was applied, the coated particleswere dried at 40° C. for 24 hours. The coated product was producedhaving 5% or 10% by weight polymer coating.

The release of sulfamic acid was measured using a pH meter, as describedin the Test method for the “Release Profile Measurement—Release ofCoated Sulfamic Acid Test” above. The results are tabulated in Table 1below.

TABLE 1 TA_(D) - A TA_(D) - B Time (min) (5% coating) (10% coating) 00.0 0.0 2 2.1 1.0 4 9.0 1.7 6 18.2 2.7 8 28.1 3.9 10 37.6 5.2 15 60.07.9 20 77.5 11.9 25 89.1 15.4 30 96.3 20.8 40 97.3 33.3 50 97.9 46.6 6099.4 59.1 80 78.2 100 90.4

FIG. 9 is a graphical plot of release profiles of poly(meth)acrylatecoated sulfamic acid. These triggering agents showed sigmoidal releaseprofiles. And the release rate was controlled by the amount of coatingpolymer.

Example 2 Preparation of poly(meth)acrylate Coated Calcium Formate(TA_(D)-C and TA_(D)-D)

The general procedures outlined in Example 1 were used to apply EUDRAGITRS 30D polymer coating on calcium formate particles (commerciallyavailable from Fisher Scientific). The coated particles consisted 5% or10% by weight polymer coating.

The release of calcium formate was measured according to the generalprocedures described in the test method, “Release of Coated CalciumFormate Test”. The results are tabulated in Table 2 below.

TABLE 2 TA_(D) - C TA_(D) - D Time (min) (5% coating) (10% coating) 00.0 0.0 2 49.4 18.8 5 67.8 45.3 10 93.2 73.3 20 98.6 91.4 30 99.6 94.945 99.6 96.9 60 99.6 98.7

FIG. 10 is a graphical plot of release profiles of poly(meth)acrylatecoated calcium formate. These triggering agents showed singular releaseprofiles. And the release rate was controlled by the amount of coatingpolymer.

Example 3 Calcium Formate Coated with Cellulose Acetate (TA_(D)-E)

400 g of calcium formate particles (commercially available from FisherScientific, particle size as shown in Table 4) were stirred in aKITCHEN-AID mixer. 45 ml of cellulose acetate solution (EASTMANCA-398-3, 20% in acetone) was added onto the particles dropwise using asyringe over a period of two minutes. After stirring the mixture for oneminute, the coated particles were air-dried then dried in oven at 50° C.for two hours. The dried material was sieved to remove particles greaterthan 850 μm and smaller than 150 μm. The release profile of calciumformate was measured according to the general procedure described in thetest method, “Release of Coated Calcium Formate Test”. The results aretabulated in Table 3 below.

Example 4 Calcium Formate Coated with Cellulose Acetate and EthylCellulose (TA_(D)-F)

400 g of calcium form ate particles (commercially available from FisherScientific, particle size as shown in Table 4) were stirred in aKITCHEN-AID mixer. 60 ml of cellulose acetate solution (EASTMANCA-398-3, 20% in acetone) was added onto the particles dropwise using asyringe over a period of two minutes. After stirring the mixture for oneminute, the coated particles were air-dried. Then the particles werecoated with 70 ml of ethyl cellulose solution (commercially availablefrom Sigma-Aldrich, 10 cP, 20% in ethanol) in the same manner to give asecond layer of coating. Then the sample was dried in oven at 50° C. fortwo hours. The dried material was sieved to remove particles greaterthan 850 μm and smaller than 150 μm. The release profile of calciumformate was measured according to the general procedure described in thetest method, “Release of Coated Calcium Formate Test”. The results aretabulated in Table 3 below.

TABLE 3 Time (min) TA_(D) - E TA_(D) - F 0 0.0 0.0 2 60.8 7.3 5 92.112.6 10 98.1 22.5 15 99.2 30.5 20 99.3 37.1 30 99.3 51.3 45 99.9 60.7 6099.4 64.0 120 99.2 71.1

FIG. 11 is a graphical plot of release profiles of cellulose acetate orcellulose acetate/ethyl cellulose coated calcium formate. Thesetriggering agents showed singular release profiles.

Example 5 Preparation of Sodium Carboxymethyl Cellulose Coated CalciumFormate (TA_(D)-G)

400 g of calcium formate particles (commercially available from FisherScientific, particles size as shown in Table 4) were stirred in aKITCHEN-AID mixer. 40 ml of sodium carboxymethyl cellulose (CMC)solution (1% in water) was added onto the particles dropwise using asyringe over a period of one minute. After stirring the mixture for oneadditional minute, the coated particles were dried in oven at 110° C.for 30 minutes. Then the sample was sieved using 20/80 mesh sieves (U.S.Sieve Series). The particles on the 80 mesh sieve were collected toafford 320 grams of product. The coated particles showed fast releaserate in water, 77% released at one minute, 100% released at 2 minutes.The coated sample had larger particle size than the uncoated sample, asshown in Table 4 below.

TABLE 4 Particle size distribution of CMC coated calcium formate(TA_(D) - G) <180 850-300 300-180 microns Sample microns (%) microns (%)(%) Commercial calcium formate 8 32 60 TA_(D) - G 77.4 22.5 0.1 (CMCcoated calcium formate)

Example 6 Preparation of poly(meth)acrylate Coated Sodium Carbonate(TA_(R)-A to TA_(R)-D)

The general procedures outlined in Example 1 were used to apply EUDRAGITRS 30D polymer coating on sodium carbonate particles (commerciallyavailable from Sigmal-Aldrich, particle size between 100-20 mesh, U.S.Sieve Series). The coated particles consisted 5%, 10%, 18%, or 27% byweight polymer coating.

The release of sodium carbonate was measured according to the generalprocedures described in the test method, “Release of Coated SodiumCarbonate”. The results are tabulated in Table 5 below.

TABLE 5 TA_(R) - B TA_(R) - A (10% TA_(R) - C TA_(R) - D Time (min) (5%coating) coating) (18% coating) (27% coating) 0 0.0 0.0 0.0 0.0 2 3.60.3 0.4 0.2 4 9.5 0.6 0.5 0.3 6 15.7 1.1 0.7 0.4 8 22.1 1.8 0.8 0.4 1028.4 3.6 1.0 0.5 15 43.5 10.4 1.5 0.8 20 56.5 17.3 3.9 1.0 25 66.8 25.08.1 1.4 30 75.2 32.3 12.9 2.1 40 86.1 47.5 22.6 5.9 50 91.9 60.6 32.612.7 60 95.0 71.6 42.5 20.2 80 99.0 86.0 61.3 35.6 100 92.4 76.3 49.4120 96.1 84.7 60.0 150 89.9 72.9 210 98.9 94.8 280 99.8

FIG. 12 is a graphical plot of release profiles of poly(meth)acrylatecoated sodium carbonate. These triggering agents showed sigmoidalrelease profiles.

Example 7 Preparation of MPP Coated Sodium Carbonate (TA_(R)-E,TA_(R)-F)

400 g of sodium carbonate particles (100-20 mesh) was put in aone-gallon plastic bucket. The bucket was placed on a Retch Shaker tofluidize the particles. Maleated polypropylene (MPP) emulsion (20% inwater, commercially available from Chemcor, Chester, N.Y.) was sprayedonto particles using a spraying gun over a period of 20 minutes. Thecoated particles were dried in oven at 50° C. for 2 days. The coatedparticles consisted of 2% or 6% by weight of polymer coating.

The release of sodium carbonate was measured according to the generalprocedures described in the test method, “Release of Coated SodiumCarbonate”. The results are tabulated in Table 6 below.

TABLE 6 TA_(R) - E TA_(R) - F Time (2% coating) (6% coating) 0 0.0 0.0 220.2 17.7 5 42.1 26.9 10 69.5 48.6 15 87.8 61.4 20 95.7 81.1 30 99.194.1 40 99.6 96.2 60 100.0 96.2

FIG. 13 is a graphical plot of release profiles of maleatedpolypropylene coated sodium carbonate. These triggering agents showedsingular release profiles.

Examples 8-13 SAP Swelling/Deswelling by Forming Insoluble Salts

FAVOR SXM-9300, a commercially available SAP manufactured by EvonikStockhausen Inc., Greensboro, N.C., was used to demonstrate the swellingand deswelling triggered by formation of insoluble salts. The SAP wasfirst exposed to a salt solution containing multivalent cations. Then itwas exposed to a second salt solution containing anions which is able tocomplex with the multivalent cations of the first salt to form aninsoluble salt having solubility product constant Ksp<10⁻⁵. Incomparative example 13, KCl was used as the deswell triggering agent andNa₂SO₄ as the reswell triggering agent.

Specifically, 0.20 g of superabsorbent polymer composition was placed ina teabag. The first centrifuge retention capacity of the SAP sample wastested according to the Centrifuge Retention Capacity Test. Then theteabag was immersed in a deswell solution which was prepared bydissolving specific amount of the deswell triggering agent in 10 g of0.9% by weight sodium chloride solution. After 10 minutes of soakingtime, the bag was placed in a centrifuge and the retention capacity wasmeasured to give the second centrifuge retention capacity. Then the bagwas immersed in a reswell solution which was prepared by dissolvingspecific amount of the reswell triggering agent in 20 g of 0.9% byweight sodium chloride solution. After 20 minutes of soaking time, thebag was placed in a centrifuge and the retention capacity was measuredto give the third centrifuge retention capacity. Results of the testingare summarized in Table 7 below. Solubility Product Constants listed inTable 7 refer to the salts formed from the cations of the first triggerchemical and the anions of the second trigger chemical. They can beobtained from an online source:http://www.csudh.edu/oliver/chemdata/data-ksp.htm.

TABLE 7 Mixing ratio of Deswell Reswell SAP/deswell triggeringtriggering agent/reswell 1^(st)/2^(nd)/3^(rd) Solubility Product ExampleSAP agent agent agent CRC (g/g) Constant* 8 SXM9300 AlCl₃ Na₅P₃O₁₀1/0.2/0.33 29.5/19.3/26.8 6.3 × 10⁻¹⁹ 9 SXM9300 CaCl₂ Na₂CO₃ 1/0.4/0.3829.5/11.0/18.0 3.8 × 10⁻⁹ 10 SXM9300 CaCl₂ Na₅P₃O₁₀ 1/0.2/0.5329.5/20.5/25.8   1 × 10⁻²⁶ 11 SXM9300 CaCl₂ Na₅P₃O₁₀ 1/0.4/129.5/11.0/23.7   1 × 10⁻²⁶ 12 SXM9300 calcium Na₂CO₃ 1/0.4/0.429.5/12.5/16.7 3.8 × 10⁻⁹ formate 13 SXM9300 KCl Na₂SO₄ 1/0.4/0.429.5/26/26 >10⁻⁵

The results from Examples 8-12 demonstrated the ability to deswell SAPby exposing the swollen SAP to a salt solution comprising cations havingan ionized valence of two or more. In addition, the results also showedthat the deswelled SAP could reswell in the presence of a second saltsolution containing anions which are able to complex with the cations ofthe first salt to form an insoluble salt having solubility productconstant Ksp<10⁻⁵. In Example 13, the cation (K⁺) of the first salt hasan ionized valence of less than two and the anions (SO₄ ²⁻) of thesecond salt form a soluble salt with the cations (K⁺) of the first salt(KCl). In this case, the SAP failed to exhibit an effective deswell andreswell. Slightly reduced 2^(nd) and 3^(rd) CRC capacities are mainlydue to salt poisoning effect caused by the soluble first and secondsalts.

Examples 14-16 SAP Swelling/Deswelling by Forming Insoluble Salts

Table 8 below lists the swell/deswell/reswell evaluation results forSAP-B, SAP-D, and SAP-F from the Centrifuge Retention Capacity Test.Superabsorbent polymers with lower degree of neutralization (SAP-D andSAP-F, 40-60% DN) demonstrated improved reswelling capacity comparedwith the SAP having regular degree of neutralization (about 70% DN).

TABLE 8 Mixing ratio of Reswell SAP/deswell Solubility Deswelltriggering agent/reswell 1^(st)/2^(nd)/3^(rd) CRC Product Ex SAPtriggering agent agent agent (g/g) Constant* 14 SAP-B calcium Na₂CO₃1/0.3/0.6 29.4/16.0/20.7 3.8 × 10⁻⁹ formate 15 SAP-D calcium Na₂CO₃1/0.3/0.6 29.4/16.1/22.6 3.8 × 10⁻⁹ formate 16 SAP-F calcium Na₂CO₃1/0.2/0.2 33/26.5/31.8 3.8 × 10⁻⁹ formate

Examples 17-21 Swelling/Deswelling of Low DN Superabsorbent Polymers

Superabsorbent polymer compositions having 40-60% of the degree ofneutralization (DN) were used to demonstrate the mass efficiency andreswelling capacity improvement over the commercial availablesuperabsorbent polymers, such as SXM-9300. Sulfamic acid was used as thedeswell triggering agent and sodium carbonate was used as the reswelltriggering agent. The evaluations were performed following the generalprocedures as described in Examples 8-13. The results are tabulated inTable 9 below.

TABLE 9 Reswell Mixing ratio of SAP/ Deswell triggering deswellagent/reswell 1^(st)/2^(nd)/3^(rd) CRC Ex SAP triggering agent agentagent (g/g) 17 SAP-A Sulfamic acid Na₂CO₃ 1/0.4/0.4 29.5/17.9/26.2SXM9300 18 SAP-C Sulfamic acid Na₂CO₃ 1/0.2/0.4 30/21.9/31.2 19 SAP-CSulfamic acid Na₂CO₃ 1/0.4/0.4 30/14.1/29.9 20 SAP-E Sulfamic acidNa₂CO₃ 1/0.2/0.4 29.1/18/29.5 21 SAP-E Sulfamic acid Na₂CO₃ 1/0.4/0.429.1/11/29.9

As clearly seen in Table 9, SAPs with lower degree of neutralization(SAP-C and SAP-E) showed improved reswelling capacity and massefficiency compared with the polymer with regular degree ofneutralization, such as SXM-9300.

Example 22

Absorbent compositions comprising SXM-9300 and poly(meth)acrylate coatedsulfamic acid were used to demonstrate the swelling/deswelling behaviorof the absorbent compositions. A mixture of SXM-9300 and coated sulfamicacid (triggering agents TA_(D)-A or TA_(D)-B) was placed in a cylinderwith screen bottom and the absorption capacity was measured according tothe general procedures described in the Swell/Deswell/Reswell Test ofthe absorbent composition. The results are tabulated in Table 10 below.

TABLE 10 Wt. ratio of Starting Maximum SAP and point of swellingTriggering triggering deswelling capacity SAP agent agent step (min)(g/g) SXM-9300 TA_(D) - A 1/1.6 11 26 SXM-9300 TA_(D) - A 1/1.2 13.527.4 SXM-9300 TA_(D) - A 1/0.8 14.6 29 SXM-9300 TA_(D) - B 1/1.2 33 33.5

From the results in Table 10 and FIG. 14, it can be seen that theswelling capacity and deswelling time was controlled by the polymercoating level in the triggering agent as well as by the mixing ratio ofSAP and the triggering agent.

Examples 23-27

Table 11 lists the absorbent compositions comprising a superabsorbentpolymer or superabsorbent polymer composition, a deswell triggeringagent comprising sulfamic acid, and a reswell triggering agentcomprising a basic material such as sodium carbonate. Theswell/deswell/reswell curves were measured according to the generalprocedures described in the Swell/Deswell/Reswell Test of the absorbentcomposition.

TABLE 11 Absorbent compositions having triggering agents Deswell ReswellExamples SAP triggering agent triggering agent Ratio 23 SXM-9300TA_(D) - A TA_(R) - B 1:1.2:1.2 24 SXM-9300 TA_(D) - A TA_(R) - C1:1.2:1.2 25 SAP-B TA_(D) - A TA_(R) - B 1:1.2:1.2 26 SAP-C TA_(D) - ATA_(R) - B 1:0.6:1 27 SAP-D TA_(D) - A TA_(R) - B 1:0.6:1

FIG. 15 is a graphical plot of swell/deswell/reswell curves of a drymixture of SXM-9300 with both the deswell and reswell triggering agentsfor Examples 23-24 and as shown in Table 11. In these examples, thestarting point for the reswelling step was controlled by the releaserate of the reswell triggering agent.

FIG. 16 is a graphical plot of swell/deswell/reswell curves for Example25 and as shown in Table 11. In this example, SAP-B, a superabsorbentpolymer composition comprising an encapsulated blowing agent, gaveimproved swelling capacity due to fast absorption rate compared withSXM-9300.

FIG. 17 is a graphical plot of swell/deswell/reswell curves for Examples26-27 and as shown in Table 11. In these examples, SAP-C and SAP-D,superabsorbent polymer compositions having about 50% DN, affordedimproved swelling and reswelling capacities and mass efficiency comparedwith SXM-9300. SAP-D exhibits an improved swelling capacity over SAP-Calso due to its fast absorption rate.

Examples 28-32

Table 12 summarizes the absorbent compositions comprising SXM-9300 or asuperabsorbent polymer composition of the present invention, a deswelltriggering agent comprising multivalent cations, and a reswelltriggering agent comprising anions which are able to complex with themultivalent cations of the deswell triggering agent to form an insolublesalt having solubility product constant K_(sp)<10⁻⁵. Theswell/deswell/reswell curves were measured according to the generalprocedures described in the Swell/Deswell/Reswell Test.

TABLE 12 Absorbent compositions having triggering agents Deswell ReswellExamples SAP triggering agent triggering agent Ratio 28 SXM-9300TA_(D) - C TA_(R) - A 1:0.8:1.6 29 SAP-B TA_(D) - C TA_(R) - A 1:1:1.230 SAP-B TA_(D) - F TA_(R) - C 1:1:1 31 SAP-D TA_(D) - F TA_(R) - C1:0.4:0.8 32 SAP-D TA_(D) - F TA_(R) - C 1:0.5:1

FIG. 18 is a graphical plot of swell/deswell/reswell curves for Example28 and as shown in Table 12 as measured by the Swell/Deswell/ReswellTest. In this example, the SAPs exhibited swell/deswell/reswell behaviorafter exposure to 0.9% saline solution.

FIG. 19 is a graphical plot of swell/deswell/reswell curves for Examples29-30 and as shown in Table 12 as measured by Swell/Deswell/ReswellTest. In these examples, SAP-B, a superabsorbent polymer compositioncomprising an encapsulated blowing agent, afforded improved swellingcapacity compared with SXM-9300.

FIG. 20 is a graphical plot of swell/deswell/reswell curves for Examples31-32 and as shown in Table 12 as measured by Swell/Deswell/ReswellTest. In these examples, SAP-D, a superabsorbent polymer compositioncomprising an encapsulated blowing agent and having about 50% DN,demonstrated the advantage of improved swelling and reswelling capacityand mass efficiency improvement.

Examples 33 to 38

Handsheets were prepared using standard airforming handsheet equipment.The resulting handsheet composites had dimensions of 25.4 cm wide by43.2 cm long.

A modification to the forming unit was used which allowed individual 7.6cm long zones to be made with specific amounts of pulp fibers andparticulate materials (either SAP, or triggering agents, or combinationsthereof) (see Table 13 below). However, it is noted that the two outsidezones produced webs that were 10.2 cm long.

Fluff used was fiberized COOSASORB 100% Southern Softwood pulp(available from Bowater Corporation, having a place of business in CoosaPines, Ala., U.S.A.). The SAP for Example 33 was FAVOR SXM-9300(available from Evonik Stockhausen, Inc., having a place of business inGreensboro, N.C., U.S.A.). The superabsorbent polymer composition forExamples 34-38 was SAP-D. The deswell triggering agent used in Examples34-38 was TA_(D)-A. The reswell triggering agent used in Examples 34-38was TA_(R)-C.

For Examples 34-38, for each zone, the required amount of particulatematerials (SAP-D, TA_(D)-A, and TA_(R)-C) was measured (see Table 13)and hand mixed in a beaker prior to web formation.

The fluff and particulate materials were formed onto a forming tissuehaving a basis weight of about 16.6 gsm (available as WHITE WRAP SHEET,available from Cellu Tissue Holdings, Inc., having a place of businessin East Hartford, Conn., U.S.A.).

The handsheets were produced with the following procedure. A sheet ofthe forming tissue was placed on the bottom of the former. Then, thesuperabsorbent polymer composition (along with any triggering agents)and the fluff were each divided into about equal portions (i.e. 6portions of fluff and 5 portions of particulate materials) for each zoneidentified in Table 13 below. Each fluff portion and particulatematerials portion was alternatively introduced into the top of theformer, allowing the compressed air to mix the fluff and particulatematerials while the vacuum drew the material through the forming chamberand onto the forming tissue. This process was continued until the lastportion of fluff was consumed, forming a substantially uniformdistribution of fluff and particulate materials. This yielded absorbentcomposites which had a basis weight (of combined superabsorbent polymercomposition and fluff) of 700 gsm. Any triggering agents added within azone resulted in a total basis weight higher than 700 gsm for that zone.

Following web formation, another layer of the above forming tissue wasplaced on top of the formed composite.

TABLE 13 Zoned Handsheets with Deswell and Reswell Triggering agents ina Zoned Configuration Amount of components used to produced zonedhandsheets - each zone 7.6 cm long by 25.4 cm wide (except zones 1 and 5which are 7.6 cm long × 25.4 cm wide) Zone 1 Zone 2 Zone 3 Example No.SAP TA_(D)-A TA_(R)-C fluff SAP TA_(D)-A TA_(R)-C fluff SAP TA_(D)-ATA_(R)-C fluff Example 33 10.84 g 0 g 0 g 7.23 g 8.13 g   0 g   0 g 5.42g 8.13 g   0 g   0 g 5.42 g Example 34 10.84 g 6.50 g   10.84 g    7.23g 8.13 g 5.42 g 8.13 g 5.42 g 8.13 g 5.42 g 8.13 g 5.42 g Example 3510.84 g 0 g 0 g 7.23 g 8.13 g 5.42 g 8.13 g 5.42 g 8.13 g 5.42 g 8.13 g5.42 g Example 36 10.84 g 0 g 0 g 7.23 g 8.13 g 2.71 g 4.07 g 5.42 g8.13 g 5.42 g 8.13 g 5.42 g Example 37 10.84 g 0 g 0 g 7.23 g 8.13 g1.36 g 2.03 g 5.42 g 8.13 g 2.71 g 4.07 g 5.42 g Example 38 10.84 g 0 g0 g 7.23 g 8.13 g   0 g   0 g 5.42 g 8.13 g 5.42 g 8.13 g 5.42 g Amountof components used to produced zoned handsheets - each zone 7.6 cm longby 25.4 cm wide (except zones 1 and 5 which are 7.6 cm long × 25.4 cmwide) Zone 4 Zone 5 Example No. SAP TA_(D)-A TA_(R)-C fluff SAP TA_(D)-ATA_(R)-C fluff Example 33 8.13 g   0 g   0 g 5.42 g 10.84 g 0 g 0 g 7.23g Example 34 8.13 g 5.42 g 8.13 g 5.42 g 10.84 g 6.50 g   10.84 g   7.23 g Example 35 8.13 g 5.42 g 8.13 g 5.42 g 10.84 g 0 g 0 g 7.23 gExample 36 8.13 g 2.71 g 4.07 g 5.42 g 10.84 g 0 g 0 g 7.23 g Example 378.13 g 1.36 g 2.03 g 5.42 g 10.84 g 0 g 0 g 7.23 g Example 38 8.13 g   0g   0 g 5.42 g 10.84 g 0 g 0 g 7.23 g Example 33 includes commercialsuperabsorbent SXM-9300 while Examples 34-38 include SAP-D.

The resulting handsheet composite was compressed to a thickness ofapproximately 3.5 mm prior to testing, using a CARVER PRESS model #4531(available from Carver, Inc., having a place of business in Wabash, Ind.U.S.A.).

Following handsheet preparation and densification, samples were cut to7.6 cm wide by 38.1 cm long such that each zone above ended up being 7.6cm long (i.e. 2.5 cm removed from length of zones 1 and 5). Thisresulted in the amounts of superabsorbent polymer composition, fluff,TA_(D)-A, TA_(R)-C in each 7.6 cm×7.6 cm zone as identified in Table 14below.

TABLE 14 Absorbent materials in a Zoned Configuration A 38.1 cm long ×7.6 cm wide composite with 5 equal zones and each zone having a size of7.6 × 7.6 cm Zone 1 Zone 2 Zone 3 Example No. SAP TA_(D)-A TA_(R)-Cfluff SAP TA_(D)-A TA_(R)-C fluff SAP TA_(D)-A TA_(R)-C fluff Example2.44 g 0 g 0 g 1.63 g 2.44 g   0 g   0 g 1.63 g 2.44 g   0 g   0 g 1.63g 33 Example 2.44 g 1.46 g   2.44 g   1.63 g 2.44 g 1.46 g 2.44 g 1.63 g2.44 g 1.46 g 2.44 g 1.63 g 34 Example 2.44 g 0 g 0 g 1.63 g 2.44 g 1.46g 2.44 g 1.63 g 2.44 g 1.46 g 2.44 g 1.63 g 35 Example 2.44 g 0 g 0 g1.63 g 2.44 g 0.73 g 1.22 g 1.63 g 2.44 g 1.46 g 2.44 g 1.63 g 36Example 2.44 g 0 g 0 g 1.63 g 2.44 g 0.36 g 0.61 g 1.63 g 2.44 g 0.73 g1.22 g 1.63 g 37 Example 2.44 g 0 g 0 g 1.63 g 2.44 g   0 g   0 g 1.63 g2.44 g 1.46 g 2.44 g 1.63 g 38 A 38.1 cm long × 7.6 cm wide compositewith 5 equal zones and each zone having a size of 7.6 × 7.6 cm Zone 4Zone 5 Example No. SAP TA_(D)-A TA_(R)-C fluff SAP TA_(D)-A TA_(R)-Cfluff Example 2.44 g   0 g   0 g 1.63 g 2.44 g 0 g 0 g 1.63 g 33 Example2.44 g 1.46 g 2.44 g 1.63 g 2.44 g 1.46 g   2.44 g   1.63 g 34 Example2.44 g 1.46 g 2.44 g 1.63 g 2.44 g 0 g 0 g 1.63 g 35 Example 2.44 g 0.73g 1.22 g 1.63 g 2.44 g 0 g 0 g 1.63 g 36 Example 2.44 g 0.36 g 0.61 g1.63 g 2.44 g 0 g 0 g 1.63 g 37 Example 2.44 g   0 g   0 g 1.63 g 2.44 g0 g 0 g 1.63 g 38 Example 33 includes commercial superabsorbent SXM-9300available from Evonik Stockhausen, Inc. while Examples 34-38 includeSAP-D.

Testing of Examples 33-38

7.6 cm wide by 38.1 cm long pieces of Examples 33-38 were subjected tothe Cradle Intake Test. The distribution of liquid in the lengthwisedirection of the examples was determined by x-ray imaging as describedin the Cradle Intake Test method description.

The results of fluid distribution analysis are shown in Table 15 below.

TABLE 15 Liquid amount remaining in the insult area after each liquidinsult. Liquid Amount in Target Region from 13^(th) to 24^(th) cm (totalcomposite length 38.1 cm) After 1^(st) After 2^(nd) After 3^(rd) ExampleNo. Insult Insult Insult Example 33 55 g 114 g  163 g Example 34 54 g 94g 127 g Example 35 56 g 96 g 130 g Example 36 54 g 94 g 124 g Example 3758 g 107 g  136 g Example 38 57 g 107 g  129 g

As can be seen in Table 15, after the 2^(nd) and 3^(rd) insults, all theexamples containing triggering agents (Examples 34-38) show a reductionin the amount of liquid remaining in the insult area compared to Example33. This indicates more liquid being distributed throughout theabsorbent composite.

Examples 39-44

Handsheets were prepared using standard airforming handsheet equipment.The resulting handsheet composites had dimensions of 25.4 cm wide by43.2 cm long.

Fluff used was fiberized COOSASORB 100% Southern Softwood pulp. The SAPfor Comparative Example 39 was FAVOR SXM-9300. The SAP for ComparativeExample 40 and Examples 41-44 was SAP-D. The deswell triggering agentused in Examples 41 and 43 was TA_(D)-G. The deswell triggering agentused in Examples 42 and 44 was TA_(D)-E. The reswell triggering agentused in Examples 41-44 was TA_(R)-F.

31.46 g of fluff and 47.18 g of SAP was formed onto a WHITE WRAP SHEETforming tissue having a basis weight of about 16.6 gsm. This amount ofSAP and fluff yielded an absorbent composite with a basis weight of 717gsm over the 25.4 cm wide by 43.2 cm long handsheet produced by thisequipment.

The handsheets were produced with the following procedure. A sheet ofthe forming tissue was placed on the bottom of the former. Then, the SAPand the fluff were each divided into about equal portions (i.e. 6portions of fluff and 5 portions of SAP). Each fluff portion and SAPportion was alternatively introduced into the top of the former,allowing the compressed air to mix the fluff and SAP while the vacuumdrew the materials through the forming chamber and onto the formingtissue. This process was continued until the last portion of fluff wasconsumed, forming a substantially uniform distribution of fluff and SAP.

Following web formation, another layer of the above forming tissue wasplaced on top of the formed composite. The composite web was compressedto a thickness of approximately 3.6 mm prior to testing using a CARVERPRESS model #4531. Samples of the airformed handsheets were cut to 2.5cm width by 38.1 cm length.

The following additional procedure was then followed for Examples 41-44:(see FIG. 21)

-   -   1. A 2.5 cm wide by 38.1 cm long piece of the above identified        tissue was laid down on a flat, horizontal surface, and the        central 22.9 cm in the lengthwise direction was marked.    -   2. The required amount of the triggering agent identified in        Table 16 (4^(th) column) was uniformly sprinkled onto the        tissue, within the marked 22.9 cm long section, using a        household salt shaker.    -   3. The appropriate 2.5 cm by 38.1 cm airformed handsheet (with        the forming tissue still on the top and bottom) was placed onto        the triggering agent (from step 2).    -   4. Another layer of the above identified tissue, with the        central 7.6 cm in the lengthwise direction marked, was placed on        top of the airformed handsheet from step 3.    -   5. The required amount of the triggering agent identified in        Table 16 (3^(rd) column) was uniformly sprinkled onto the        tissue, within the marked 7.6 cm long section, using a household        salt shaker.    -   6. Another 2.5 cm×38.1 cm layer of the above identified tissue        was then placed on top of the triggering agent from step 5.

The result was an absorbent system with triggering agents located in adiscrete layer. FIG. 21 shows a cross-section view of a representativeabsorbent system 300 of Examples 41-44, where the system 300 has anabsorbent composite 310 which comprises the SAP and fluff, a discretelayer 342 which includes the top triggering agent located on top-side ofthe composite 310, and a discrete layer 343 which includes the bottomtriggering agent located on the bottom-side of the composite 310.

Testing of Examples 39-44

Examples 39-44 were subjected to the Horizontal Distribution test. Thelength of the wetted area of the absorbent system was determined byvisual observation as indicated in the Horizontal Distribution testmethod. The results can be seen in Table 16 below.

TABLE 16 Wetted Length of Systems with Deswell and Reswell TriggeringAgents in Layered Configuration after 2^(nd) Fluid Insult Deswell andReswell Triggering Agents in Layered Configuration Bottom Absorbent Top(center (center Wetted Composite 7.6 cm 22.9 cm Length after (38.1 × 2.5cm) - in length in length 2^(nd) Insult Example No. 717 gsm direction)direction) (cm) Comparative 60% None None 23.9 Example 39 9300/40% fluffComparative 60% None None 20.8 Example 40 SAP-D/40% fluff Example 41 60%1.25 g 2.50 g 32.5 SAP-D/40% TA_(D) - G TA_(R) - F fluff Example 42 60%1.25 g 2.50 g 30.2 SAP-D/40% TA_(D) - E TA_(R) - F fluff Example 43 60%2.50 g 1.25 g 27.4 SAP-D/40% TA_(R) - F TA_(D) - G fluff Example 44 60%2.50 g 1.25 g 26.9 SAP-D/40% TA_(R) - F TA_(D) - E fluff

As can be seen by the results in Table 16 (last column) theincorporation of the triggering agents to the system result in the fluidbeing distributed over a longer distance than either of ComparativeExamples 39 and 40 which contain only SAP and fluff.

Examples 45-49

Handsheets were prepared using standard airforming handsheet equipment.The resulting handsheet composites had dimensions of 25.4 cm wide by43.2 cm long.

Fluff used was fiberized COOSASORB 100% Southern Softwood pulp. The SAPfor Comparative Example 45 was FAVOR SXM-9300. The superabsorbentpolymer composition for Comparative Example 46 and Examples 47-49 wasSAP-D. The deswell triggering agent used in Examples 47 to 49 wasTA_(D)-G. The reswell triggering agent used in Examples 47 to 49 wasTA_(R)-F.

31.46 g of fluff and 47.18 g of SAP were formed onto a WHITE WRAP SHEETforming tissue having a basis weight of about 16.6 gsm. This amount ofSAP and fluff yielded an absorbent composite with a basis weight of 717gsm over the 25.4 cm wide by 43.2 cm long handsheet produced by thisequipment.

The handsheets were produced with the following procedure. A sheet ofthe forming tissue was placed on the bottom of the former. Then, the SAPand the fluff were each divided into about equal portions (i.e. 6portions of fluff and 5 portions of SAP). Each fluff portion and SAPportion was alternatively introduced into the top of the former,allowing the compressed air to mix the fluff and SAP while the vacuumdrew the materials through the forming chamber and onto the formingtissue. This process was continued until the last portion of fluff wasconsumed, forming a substantially uniform distribution of fluff and SAP.

Following web formation, another layer of the above forming tissue wasplaced on top of the formed composite. The composite was compressed to athickness of approximately 3.6 mm prior to testing using a CARVER PRESSmodel #4531. Samples of the airformed handsheets were cut to 2.5 cmwidth by 38.1 cm length.

To complete the systems for Examples 47 to 49: (see FIG. 22)

-   -   1. A 38.1 cm long by 2.5 cm wide piece of the above identified        tissue was laid down on a flat, horizontal surface, with every        7.6 cm in the lengthwise direction marked.    -   2. The required amount of the reswell triggering agent        identified in Table 17 (6^(th)-8^(th) column) was uniformly        sprinkled onto the tissue in the middle three zones (zones 2, 3,        and 4) with a household salt shaker.    -   3. The appropriate 38.1 cm by 2.5 cm airformed handsheet (with        the forming tissue still on the top and bottom) was placed onto        the triggering agent (from step 2).    -   4. Another layer of the above identified tissue with every 7.6        cm in the lengthwise direction marked was placed on top of the        airformed handsheet from step 3.    -   5. The required amount of the deswell triggering agent        identified in Table 17 (3^(rd)-5^(th) column) was uniformly        sprinkled onto the tissue in the middle three zones (zones 2, 3,        and 4) with a household salt shaker.    -   6. Another 38.1 cm×2.5 cm layer of the above identified tissue        was placed on top of the triggering agent from step 5.

The result was an absorbent system with triggering compositions locatedin a target zone of a discrete layer. FIG. 22 shows a cross-section viewof a representative absorbent system 400 of Examples 45-49, where thesystem 400 has an absorbent composite 410 which comprises the SAP 412and fluff; a discrete layer 442 which includes the deswell triggeringagent 414 located on top-side of the composite 410 and includes zone 2452, zone 3 453, and zone 4 454; and a discrete layer 443 which includesthe reswell triggering agent 416 located on the bottom-side of thecomposite 410 and includes zone 2 452, zone 3 453, and zone 4 454.

Testing of Examples 45 to 49

Comparative Examples 45 and 46 and Examples 47-49 were subjected to theHorizontal Distribution Test. The length of the wetted area of theabsorbent system was determined by visual observation as indicated inthe Horizontal Distribution Test method. The results can be seen inTable 17 below.

TABLE 17 Wetted length after 2^(nd) insult with triggering agents in alayered configuration Deswell and Reswell Triggering agents inLayered/Zoned Configuration over Center of Composite TA_(D)-G on top ofTA_(R)-F at bottom of composite composite Wetted Absorbent (centered &three (centered & three Length Composite equal 7.62 × 2.54 cm equal 7.62× 2.54 cm after 2^(nd) (38.1 × zones) zones) Insult Example No. 2.54cm) - 717 gsm Zone 2 Zone 3 Zone 4 Zone 2 Zone 3 Zone 4 (cm) Comparative60%   0 g   0 g   0 g   0 g   0 g   0 g 23.9 Example 45 9300/40% fluffComparative 60% SAP-   0 g   0 g   0 g   0 g   0 g   0 g 20.8 Example 46D/40% fluff Example 47 60% SAP- 0.42 g 0.42 g 0.42 g 0.83 g 0.83 g 0.83g 32.5 D/40% fluff Example 48 60% SAP- 0.21 g 0.42 g 0.21 g 0.42 g 0.83g 0.42 g 31.2 D/40% fluff Example 49 60% SAP- 0.11 g 0.42 g 0.11 g 0.11g 0.83 g 0.11 g 29.5 D/40% fluff

As can be seen by the results from Table 17 (last column) above that theincorporation of as little as 45% add-on of the combined triggeringagents (relative to amount of superabsorbent polymer composition) canresult in the fluid being distributed over a longer distance than eitherof the samples containing only SAP and fluff (Comparative Examples 45and 46).

Examples 50-54 Example 50

Handsheets were prepared using standard airforming handsheet equipment.The resulting handsheet composites had dimensions of 25.4 cm wide by43.2 cm long.

Fluff used was fiberized COOSASORB 100% Southern Softwood pulp. The SAPfor Comparative Example 50 was FAVOR SXM-9300.

31.46 g of fluff and 47.18 g of SAP was formed onto a WHITE WRAP SHEETforming tissue having a basis weight of about 16.6 gsm. This amount ofSAP and fluff yielded an absorbent composite with a basis weight of 717gsm over the 25.4 cm wide by 43.2 cm long handsheet produced by thisequipment.

The handsheets were produced with the following procedure. A sheet ofthe forming tissue was placed on the bottom of the former. Then, the SAPand the fluff were each divided into about equal portions (i.e. 6portions of fluff and 5 portions of SAP). Each fluff portion and SAPportion was alternatively introduced into the top of the former,allowing the compressed air to mix the fluff and SAP while the vacuumdraws the materials through the former chamber and onto the formingtissue. This process was continued until the last portion of fluff wasconsumed, forming a substantially uniform distribution of fluff and SAP.

Following web formation, another layer of the above forming tissue wasplaced on top of the formed composite. The composite web was compressedto a thickness of approximately 3.6 mm prior to testing using a CARVERPRESS model #4531.

A die was used to cut-out a piece of the handsheet described above intoa generally hour glass shape with an overall surface area of 290 sq cm,a width in the crotch region of 6.4 cm, an overall length of 35.4 cm,and a width in the front of the piece of 10.2 cm.

This die cut absorbent was hand inserted and assembled into a typicalstep 4 size personal care product using standard components.

Example 51

Handsheets were prepared using standard airforming handsheet equipment.The resulting handsheet composites had dimensions of 25.4 cm wide by43.2 cm long.

Fluff used was fiberized COOSASORB 100% Southern Softwood pulp. Thesuperabsorbent polymer composition for Example 51 was SAP-D. The swelltriggering agent used in Example 51 was TA_(D)-F. The reswell triggeringagent used in Example 51 was TA_(R)-C.

31.46 g of fluff and 47.18 g of SAP, 23.59 g of TA_(D)-F, and 47.18 g ofTA_(R)-C were formed onto a WHITE WRAP SHEET forming tissue having abasis weight of about 16.6 gsm. This amount of particulate material andfluff yielded an absorbent composite with a basis weight of 1362 gsmover the 25.4 cm wide by 43.2 cm long handsheet produced by thisequipment.

The handsheets were produced with the following procedure. The requiredamount of particulate material; SAP-D, TA_(D)-F, and TA_(R)-C wasmeasured and hand mixed in a beaker prior to web formation. A sheet offorming tissue was placed on the bottom of the former. Then, theparticulate material and the fluff were each divided into about equalportions (i.e. 6 portions of fluff and 5 portions of particulatematerial). Each fluff portion and particulate material portion wasalternatively introduced into the top of the former, allowing thecompressed air to mix the fluff and particulate material while thevacuum drew the materials through the forming chamber and onto theforming tissue. This process was continued until the last portion offluff was consumed, forming a substantially uniform distribution offluff and particulate material.

Following web formation, another layer of the above forming tissue wasplaced on top of the formed composite. The composite web was compressedto a thickness of approximately 3.6 mm (0.2 g/cc based on mass of fiberand SAP) prior to testing using a CARVER PRESS model #4531.

A die was used to cut-out a piece of the handsheet described above intoa generally hour glass shape with an overall surface area of 290 sq cm,a width in the crotch region of 6.4 cm, an overall length of 35.4 cm,and a width in the front of the piece of 10.2 cm.

This die cut absorbent was hand inserted and assembled into a typicalstep 4 size personal care product (diaper) using standard components.

Examples 52-54

Handsheets were prepared using standard airforming handsheet equipment.The resulting handsheet composites had dimensions of 25.4 cm wide by43.2 cm long.

Fluff used was fiberized COOSASORB 100% Southern Softwood pulp. Thesuperabsorbent polymer composition for Example 52 was SAP-D. Thesuperabsorbent polymer composition for Examples 53 and 54 was SAP-F. Thedeswell triggering agent used in Examples 52-54 was TA_(D)-G. Thereswell triggering agent used in Examples 52-54 was TA_(R)-F.

31.46 g of fluff and 47.18 g of superabsorbent polymer composition wereformed onto a WHITE WRAP SHEET forming tissue having a basis weight ofabout 16.6 gsm. This amount of SAP and fluff yielded an absorbentcomposite with a basis weight of 717 gsm over the 25.4 cm wide by 43.2cm long handsheet produced by this equipment.

The handsheets were produced with the following procedure. A sheet ofthe forming tissue was placed on the bottom of the former. Then, the SAPand the fluff were each divided into about equal portions (i.e. 6portions of fluff and 5 portions of superabsorbent polymer composition).Each fluff portion and superabsorbent polymer composition portion wasalternatively introduced into the top of the former, allowing thecompressed air to mix the fluff and SAP composition while the vacuumdrew the materials through the forming chamber and onto the formingtissue. This process was continued until the last portion of fluff wasconsumed, forming a substantially uniform distribution of fluff andsuperabsorbent polymer composition.

Following web formation, another layer of the above forming tissue wasplaced on top of the formed composite. The composite web was compressedto a thickness of approximately 3.6 mm (0.2 g/cc based on mass of fiberand SAP) prior to testing using a CARVER PRESS model #4531.

A die was used to cut-out a piece of the handsheet described above intoa generally hour glass shape with an overall surface area of 290 sq cm,a width in the crotch region of 6.4 cm, an overall length of 35.4 cm,and a width in the front of the piece of 10.2 cm.

To complete the systems for Examples 52-54:

-   -   1. A 38.1 cm long by 12.7 cm wide piece of the above identified        tissue was laid down, with every 7.6 cm in the lengthwise        direction marked.    -   2. A light layer (5-25 gsm) of construction adhesive (NS34-5610        available from National Starch and Chemical, having a place of        business in Bridgewater, N.J., U.S.A.) was sprayed onto the        tissue using a spray gun, such as a PAM 600 Spraymatic available        from Fastening Technology, Inc., having a place of business in        Charlotte, N.C., U.S.A.    -   3. The required amount of the reswell triggering agent        identified in Table 18 (6^(th)-8^(th) column) was uniformly        sprinkled onto the tissue in the middle three zones (zones 2, 3,        and 4) with a household salt shaker.    -   4. The tissue/adhesive/triggering agent laminate was folded in        half (in the width-wise direction) to yield a 6.4 cm wide by        38.1 cm long sample. 2.5 cm was trimmed from the zone 5 portion        of the laminate, resulting in a tissue/adhesive/reswell        triggering agent laminate which was 6.4 cm wide by 35.6 cm long.    -   5. A 38.1 cm long by 12.7 cm wide piece of the above identified        tissue was laid down, with every 7.6 cm in the lengthwise        direction marked.    -   6. A light layer (5-25 gsm) of construction adhesive        (NS34-5610.) was sprayed onto the tissue using a spray gun, such        as a PAM 600 Spraymatic.    -   7. The required amount of the deswell triggering agent        identified in Table 18 (3^(rd)-5^(th) column) was uniformly        sprinkled onto the tissue in the middle three zones (zones 2, 3,        and 4) with a household salt shaker.    -   8. The tissue/adhesive/triggering agent laminate was folded in        half (in the width-wise direction) to yield a 6.4 cm wide by        38.1 cm long sample. 2.5 cm was trimmed from the zone 5 portion        of the laminate, resulting in a tissue/adhesive/deswell        triggering agent laminate which was 6.4 cm wide by 35.6 cm long.    -   9. The tissue/adhesive/reswell triggering agent laminate from        step 4 was laid down on a flat, horizontal workbench.    -   10. The appropriate die cut SAP/fluff absorbent composite        identified in Table 18 was positioned on top of the laminate        from step 4 such that that front end of each piece was aligned        and the laminate from step 4 was aligned in the width-wise        direction with the crotch portion of the die cut absorbent        composite.    -   11. The tissue/adhesive/deswell triggering agent laminate from        step 8 was placed on top of the die cut absorbent composite such        that that front end of each piece was aligned and the laminate        from step 8 was aligned in the width-wise direction with the        crotch portion of the die cut absorbent composite.

The above described sandwich construction of the tissue/adhesive/deswelltriggering agent laminate—die cut absorbentcomposite—tissue/adhesive/reswell triggering agent laminate was handinserted and assembled into a typical step 4 size personal care product(diaper) using standard components. FIG. 23 shows a cross-section viewof a representative absorbent system 500 of Examples 52-54, where thesystem 500 has an absorbent composite 510 which comprises the SAP 512and fluff; a discrete layer 542 which includes the deswell triggeringagent 514 located on top-side of the composite 510 and includes zone 2552, zone 3 553, and zone 4 554; and a discrete layer 543 which includesthe reswell triggering agent 516 located on the bottom-side of thecomposite 510 and includes zone 5 552, zone 5 553, and zone 4 554. FIG.24 is a top view of FIG. 23.

TABLE 18 Absorbent Product Composition and Structure Description Deswelland Reswell Triggering Agents in Layered Configuration over center ofcomposite TA_(D)-G on top of composite TA_(R)-F at bottom of composite(centered & three equal (centered & three equal 7.6 × 6.4 cm zones) 7.6× 6.4 cm zones) Example No. Diaper Core Composition Zone 2 Zone 3 Zone 4Zone 2 Zone 3 Zone 4 Comparative 12.5 g 9300/8.3 g fluff   0 g   0 g   0g   0 g   0 g   0 g Example 50 Example 51 12.5 g SAP-D/6.3 gTA_(D)-F/12.5 g TA_(R)-   0 g   0 g   0 g   0 g   0 g   0 g C/8.3 gfluff Example 52 12.5 g SAP-D/8.3 g fluff 1.04 g 1.04 g 1.04 g 2.08 g2.08 g 2.08 g Example 53 12.5 g SAP-F/8.3 g fluff 1.04 g 1.04 g 1.04 g2.08 g 2.08 g 2.08 g Example 54 12.5 g SAP-F/8.3 g fluff 0.26 g 1.04 g0.26 g 0.52 g 2.08 g 0.52 g

Testing of Examples 50-54

Twelve diapers containing absorbent systems for each of ComparativeExample 50 and Examples 51-54 were tested using the Mannequin TestMethod.

Each absorbent article tested had a conventional hour glass shapedabsorbent system. The absorbent articles each contained a 150 gsm intakelayer (i.e., surge layer) between the absorbent system and the body sideliner.

Fluid was added to the absorbent articles using “male” mannequins. Theinsult fluid (0.9 wt % aqueous sodium chloride solution) was deliveredto the products at slightly below body temperature (about 33° C.).

A relationship between the wetted area versus amount of liquid added atleakage was determined based on the amount of liquid in the product atthe time of leakage. The wetted area was determined by x-ray image asdescribed in the Mannequin Test method. A linear regression of the datapoints containing at least 50 g of liquid was used to interpolate thewetted area at 100 g liquid loading and 175 g liquid loading. Resultsare seen in Table 19 below.

TABLE 19 Wetted Area of Used Products (cm²) At a Diaper At a DiaperExample No. Loading Around 100 g Loading Around 175 g Comparative 145166 Example 50 Example 51 160 184 Example 52 150 191 Example 53 155 176Example 54 155 188

As can be seen from the results in Table 19, the wetted area for all ofthe samples comprising triggering agents show higher wetted area at both100 g of nominal loading and 175 g of nominal loading compared to thecontrol system which contained only SAP and fluff (Comparative Example50). This demonstrates increased distribution of liquid through theabsorbent pad.

Examples 55 and 56 Example 55

Handsheets were prepared using standard airforming handsheet equipment.The resulting handsheet composites had dimensions of 25.4 cm wide by43.2 cm long.

Fluff used was fiberized COOSASORB 100% Southern Softwood pulp. The SAPfor Comparative Example 55 was FAVOR SXM-9300.

31.46 g of fluff and 47.18 g of SAP was formed onto a WHITE WRAP SHEETforming tissue having a basis weight of about 16.6 gsm. This amount ofSAP and fluff yielded an absorbent composite with a basis weight of 717gsm over the 25.4 cm wide by 43.2 cm long handsheet produced by thisequipment.

The handsheets were produced with the following procedure. A sheet ofthe forming tissue was placed on the bottom of the former. Then, the SAPand the fluff were each divided into about equal portions (i.e. 6portions of fluff and 5 portions of SAP). Each fluff portion and SAPportion was alternatively introduced into the top of the former,allowing the compressed air to mix the fluff and SAP while the vacuumdrew the materials through the forming chamber and onto the formingtissue. This process was continued until the last portion of fluff wasconsumed, forming a substantially uniform distribution of fluff and SAP.

Following web formation, another layer of the above forming tissue wasplaced on top of the formed composite. The composite web was compressedto a thickness of approximately 3.6 mm prior to testing using a CARVERPRESS model #4531. Samples of the airformed handsheets were cut to 7.6cm width by 38.1 cm length.

Example 56

Handsheets were prepared using standard airforming handsheet equipment.The resulting handsheet composites had dimensions of 25.4 cm wide by43.2 cm long.

Fluff used was fiberized COOSASORB 100% Southern Softwood pulp. Thesuperabsorbent polymer composition for Example 56 was SAP-D. The deswelltriggering agent used was TA_(D)-F. The reswell triggering agent used inExample 56 was TA_(R)-C.

31.46 g of fluff and 47.18 g of superabsorbent polymer composition,23.59 g of TA_(D)-F, and 23.59 g of TA_(R)-C were formed onto a WHITEWRAP SHEET forming tissue having a basis weight of about 16.6 gsm. Thisamount of particulate material and fluff yielded an absorbent compositewith a basis weight of 1147 gsm over the 25.4 cm wide by 43.2 cm longhandsheet produced by this equipment.

The handsheets were produced with the following procedure. A sheet ofthe forming tissue was placed on the bottom of the former. The requiredamount of particulate material; SAP-D, TA_(D)-F, and TA_(R)-C wasmeasured and handmixed in a beaker prior to web formation. Then, theparticulate material and the fluff were each divided into about equalportions (i.e. 6 portions of fluff and 5 portions of particulatematerial). Each fluff portion and particulate material portion wasalternatively introduced into the top of the former, allowing thecompressed air to mix the fluff and particulate material while thevacuum drew the materials through the forming chamber and onto theforming tissue. This process was continued until the last portion offluff was consumed, forming a substantially uniform distribution offluff and particulate material.

Following web formation, another layer of the above forming tissue wasplaced on top of the formed composite. The composite web was compressedto a thickness of approximately 3.6 mm prior to testing using a CARVERPRESS model #4531. Samples of the airformed handsheets were cut to 7.6cm width by 38.1 cm length.

Testing of Examples 55 and 56

Examples 55 and 56 were tested according to the Horizontal Intake andDistribution Test. Wetted length following each liquid insult (asmentioned in the test method) are indicated in Table 20 below.

TABLE 20 Wetted Length Wetted Length Wetted Length after 1^(st) Insultafter 2^(nd) Insult after 3^(rd) Insult Example (cm) (cm) (cm)Comparative 18.5 20.5 25 Example 55 Example 56 21.0 31 >38.1* *Theentire length of the samples for Example 56 was wetted after 3^(rd)insult

As can be seen, Example 56 (containing triggering agents), results ingreater distribution of liquid for every insult compared to the control,Comparative Example 55 in which no triggering agents are present.

Examples 57-59

Handsheets were prepared using standard airforming handsheet equipment.The resulting handsheet composites had dimensions of 25.4 cm wide by43.2 cm long.

Fluff used was fiberized COOSASORB 100% Southern Softwood pulp. Thesuperabsorbent polymer composition for Examples 57-59 was SAP-F. Thedeswell triggering agent used in Examples 57 to 59 was TA_(D)-G. Thereswell triggering agent used in Examples 57 to 59 was TA_(R)-F.

31.46 g of fluff and 47.18 g of superabsorbent polymer composition wereformed onto a WHITE WRAP SHEET forming tissue having a basis weight ofabout 16.6 gsm. This amount of SAP and fluff yielded an absorbentcomposite with a basis weight of 717 gsm over the 25.4 cm wide by 43.2cm long handsheet produced by this equipment.

The handsheets were produced with the following procedure. A sheet ofthe forming tissue was placed on the bottom of the former. Then, thesuperabsorbent polymer composition and the fluff were each divided intoabout equal portions (i.e. 6 portions of fluff and 5 portions of SAP).Each fluff portion and superabsorbent polymer composition portion wasalternatively introduced into the top of the former, allowing thecompressed air to mix the fluff and superabsorbent polymer compositionwhile the vacuum drew the materials through the forming chamber and ontothe forming tissue. This process was continued until the last portion offluff was consumed, forming a substantially uniform distribution offluff and superabsorbent polymer composition.

Following web formation, another layer of the above forming tissue wasplaced on top of the formed composite. The composite web was compressedto a thickness of approximately 3.6 mm prior to testing using a CARVERPRESS model #4531. Samples of the airformed handsheets were cut to 6.4cm width by 38.1 cm length.

To complete the systems for Examples 57 to 59: (see FIG. 22)

-   1. A 38.1 cm long by 6.4 cm wide piece of the above identified    tissue was laid down on a flat, horizontal surface, with every 7.6    cm in the lengthwise direction marked.-   2. The required amount of the reswell triggering agent identified in    Table 21 (6^(th)-8^(th) column) was uniformly sprinkled onto the    tissue in the middle three zones (zones 2, 3, and 4) with a    household salt shaker.-   3. The appropriate 38.1 cm by 6.4 cm airformed handsheet (with the    forming tissue still on the top and bottom) was placed onto the    triggering agent (from step 2).-   4. Another layer of the above identified tissue with every 7.6 cm in    the lengthwise direction marked was placed on top of the airformed    handsheet from step 3.-   5. The required amount of the deswell triggering agent identified in    Table 21 (3^(rd)-5^(th) column) was uniformly sprinkled onto the    tissue in the middle three zones (zones 2, 3, and 4) with a    household salt shaker.-   6. Another 38.1 cm×6.4 cm layer of the above identified tissue was    placed on top of the triggering agent from step 5.

Testing of Examples 57 to 59

Examples 57-59 were subjected to the Horizontal Intake and Distributiontest with two modifications. 60 cc of saline solution was added duringeach liquid addition, rather than 70 cc (see step 3). Instead ofmeasuring the wetted length of the absorbent system with x-raydensitometry (see step 4), the thickness of the wet absorbent wasmeasured using a conventional thickness tester, such as Sony DigitalIndicator Model #U30A, under a measurement pressure of 3450 dynes/cm².The results can be seen in Table 21 below.

TABLE 21 Wet Thickness after 2^(nd) insult with triggering agents in alayered configuration Deswell and Reswell Triggering Agents inLayered/Zoned Configuration over Center of Composite TA_(D)-G on top ofTA_(R)-F at bottom of composite composite Wet Absorbent (centered &three (centered & three Thickness Composite equal 7.62 × 6.4 cm equal7.62 × 6.4 cm after 2^(nd) Example (38.1 × 6.4 cm) - zones) zones)Insult No. 717 gsm Zone 2 Zone 3 Zone 4 Zone 2 Zone 3 Zone 4 (mm)Example 57 60% SAP-D/40% 0.20 g 0.78 g 0.20 g 0.20 g 0.78 g 0.20 g 12.2fluff Example 58 60% SAP-D/40% 0.23 g 0.94 g 0.23 g 0.23 g 0.94 g 0.23 g11.6 fluff Example 59 60% SAP-D/40% 0.26 g 1.04 g 0.26 g 0.52 g 2.08 g0.52 g 12.5 fluff

As can be seen by the results from Table 21 (last column) above that theincorporation of as little as 23% add-on of the combined triggeringagents (relative to amount of superabsorbent polymer composition)(Example 57) can result in the fluid being distributed over a longerdistance, resulting in a reduced wet thickness in the target zone, thanthe sample containing 45% add-on of the combined trigger compositions(Example 59).

It will be appreciated that details of the foregoing examples, given forpurposes of illustration, are not to be construed as limiting the scopeof this invention. Although only a few exemplary aspects of thisinvention have been described in detail above, those skilled in the artwill readily appreciate that many modifications are possible in theexamples without materially departing from the novel teachings andadvantages of this invention. For example, features described inrelation to one example may be incorporated into any other example ofthe invention.

Accordingly, all such modifications are intended to be included withinthe scope of this invention, which is defined in the following claimsand all equivalents thereto. Further, it is recognized that many aspectsmay be conceived that do not achieve all of the advantages of someaspects, particularly of the desirable aspects, yet the absence of aparticular advantage shall not be construed to necessarily mean thatsuch an aspect is outside the scope of the present invention. As variouschanges could be made in the above constructions without departing fromthe scope of the invention, it is intended that all matter contained inthe above description shall be interpreted as illustrative and not in alimiting sense.

1. An absorbent composite comprising: an absorbent composition; whereinthe absorbent composition comprises a SAP, a deswell triggering agent(TA_(D)) and a reswell triggering agent (TA_(R)); wherein the SAP, theTA_(D) and the TA_(R) are all selected from either solubility-basedchemistry or neutralization-based chemistry groupings; wherein theTA_(D) comprises a first water-soluble solid chemical wherein the TA_(D)has a release profile for releasing the water-soluble solid chemicalwherein the release profile is selected from a singular release profileor a sigmoidal release profile; wherein the TA_(R) comprises a secondwater-soluble solid chemical wherein the reswell triggering anent has asigmoidal release profile for releasing the second water-soluble solidchemical; wherein the first water-soluble chemical has a highercumulative release than the second water-soluble chemical after exposureto aqueous fluid and before about 100% release; and wherein theabsorbent composite has a top side and an opposing bottom side.
 2. Theabsorbent composite of claim 1 wherein the SAP, TA_(D) and TA_(R) aresubstantially uniformly distributed within the composite.
 3. Theabsorbent composite of claim 1 further comprising a target zone and aperimeter region; wherein the target zone comprises the SAP, TA_(D) andTA_(R); and wherein the perimeter region comprises substantially onlythe SAP.
 4. The absorbent composite of claim 1 wherein the SAP is asuperabsorbent polymer composition.
 5. The absorbent composite of claim1 wherein the absorbent composite is present in an absorbent articlewhich further comprises a topsheet and a backsheet, wherein theabsorbent composite is disposed between the topsheet and the backsheet.6. The absorbent composite of claim 1 wherein the composite is presentin an absorbent article selected from personal care absorbent articles,health/medical absorbent articles, household/industrial absorbentarticles or sports/construction absorbent articles.
 7. An absorbentcomposite having a fibrous matrix comprising: a SAP, a deswelltriggering agent (TA_(D)) and a reswell triggering agent (TA_(R));wherein the SAP, the TA_(D) and the TA_(R) are all selected from eithersolubility-based chemistry or neutralization-based chemistry groupings;wherein the absorbent composite has a top layer, a middle layer and abottom layer; wherein the middle layer is disposed between the top layerand the bottom layer; and wherein each of SAP, TA_(D) and TA_(R) ispresent in at least one of the layers; and wherein the middle layercomprises substantially only SAP.
 8. The absorbent composite of claim 7wherein the SAP is a superabsorbent polymer composition.
 9. Theabsorbent composite of claim 7 wherein TA_(D) comprises a firstwater-soluble solid chemical wherein the TA_(D) has a release profilefor releasing the water-soluble solid chemical wherein the releaseprofile is selected from a singular release profile or a sigmoidalrelease profile; wherein the TA_(R) comprises a second water-solublesolid chemical wherein the reswell triggering agent has a sigmoidalrelease profile for releasing the second water-soluble solid chemical;and wherein the first water-soluble chemical has a higher cumulativerelease than the second water-soluble chemical after exposure to aqueousfluid and before about 100% release.
 10. The absorbent composite ofclaim 7 wherein the middle layer comprises substantially only SAP;wherein the top layer comprises substantially only TA_(D); and whereinthe bottom layer comprises substantially only TA_(R).
 11. The absorbentcomposite of claim 7 wherein the middle layer comprises substantiallyonly SAP; wherein the top layer comprises substantially only TA_(D);wherein the bottom layer comprises substantially only TA_(R); andwherein at least one of the TA_(D) and TA_(R) is located substantiallyonly in a target zone of the top layer and/or bottom layer,respectively.
 12. The absorbent composite of claim 7 wherein the middlelayer comprises substantially only SAP; and wherein the top layer andthe bottom layer each comprise substantially only TA_(D) and TA_(R)combined.
 13. The absorbent composite of claim 7 wherein the top layerand the bottom layer each comprise substantially only TA_(D) and TA_(R)combined; and wherein the TA_(D) and TA_(R) are located substantiallyonly in a target zone of at least one of the top layer and bottom layer.14. The absorbent composite of claim 7 wherein the top layer, the middlelayer, and the bottom layer each comprise substantially only one of theSAP, TA_(D) and TA_(R); and wherein none of the layers is the same. 15.The absorbent composite of claim 7 further comprising a firstintermediate layer and a second intermediate layer, wherein the firstintermediate layer is disposed between the top layer and the middlelayer, and wherein the second intermediate layer is disposed between themiddle layer and the bottom layer; wherein the top layer, the middlelayer, and the bottom layer each comprise substantially only SAP; andwherein the first intermediate layer and the second intermediate layereach comprise SAP, TA_(D) and TA_(R).
 16. The absorbent composite ofclaim 7 further comprising a first intermediate layer and a secondintermediate layer, wherein the first intermediate layer is disposedbetween the top layer and the middle layer, and wherein the secondintermediate layer is disposed between the middle layer and the bottomlayer; wherein the top layer, the middle layer, and the bottom layereach comprise substantially only SAP; wherein the first intermediatelayer comprises substantially only TA_(D); and wherein the secondintermediate layer comprises substantially only TA_(R).
 17. Theabsorbent composite of claim 7 wherein the absorbent composite ispresent in an absorbent article which further comprises a topsheet and abacksheet, wherein the absorbent composite is disposed between thetopsheet and the backsheet.
 18. The absorbent composite of claim 7wherein the composite is present in an absorbent article selected frompersonal care absorbent articles, health/medical absorbent articles,household/industrial absorbent articles or sports/construction absorbentarticles.
 19. An absorbent system comprising: a SAP, a deswelltriggering agent (TA_(D)) and a reswell triggering agent (TA_(R));wherein the SAP, the TA_(D) and the TA_(R) are all selected from eithersolubility-based chemistry or neutralization-based chemistry groupings;wherein the absorbent system comprises an absorbent composite, a topdiscrete layer, and a bottom discrete layer; wherein the absorbentcomposite includes a fibrous matrix; wherein the absorbent composite isdisposed between the top discrete layer and the bottom discrete layer;and wherein the absorbent composite, the top discrete layer, and thebottom discrete layer each comprise exclusively only one of the SAP, theTA_(D), and the TA_(R).
 20. The absorbent composite of claim 19 whereinthe SAP is a superabsorbent polymer composition.
 21. The absorbentcomposite of claim 19 wherein TA_(D) comprises a first water-solublesolid chemical wherein the TA_(D) has a release profile for releasingthe water-soluble solid chemical wherein the release profile is selectedfrom a singular release profile or a sigmoidal release profile; whereinthe TA_(R) comprises a second water-soluble solid chemical wherein thereswell triggering agent has a sigmoidal release profile for releasingthe second water-soluble solid chemical; and wherein the firstwater-soluble chemical has a higher cumulative release than the secondwater-soluble chemical after exposure to aqueous fluid and before about100% release.
 22. The absorbent system of claim 19 wherein the absorbentcomposite comprises substantially only the SAP; wherein the top discretelayer comprises substantially only the TA_(D); and wherein the bottomdiscrete layer comprises substantially only the TA_(R).
 23. Theabsorbent system of claim 19 wherein the absorbent composite comprisessubstantially only the SAP; wherein the top discrete layer comprisessubstantially only the TA_(D); wherein the bottom discrete layercomprises substantially only the TA_(R); and wherein at least one of theTA_(D) and the TA_(R) is located substantially only in a target zone ofthe top discrete layer and/or bottom discrete layer, respectively. 24.The absorbent system of claim 19 wherein the absorbent compositecomprises substantially only the SAP; and wherein the TA_(D) and theTA_(R) are located substantially only in a target zone of at least oneof the top discrete layer and/or bottom discrete layer.
 25. Theabsorbent system of claim 19 further comprising a first intermediatediscrete layer and a second intermediate discrete layer, wherein thefirst intermediate discrete layer is disposed between the top discretelayer and the absorbent composite, and wherein the second intermediatediscrete layer is disposed between the absorbent composite and thebottom discrete layer; wherein the top discrete layer and the bottomdiscrete layer each comprise substantially only SAP; wherein theabsorbent composite comprises substantially SAP; and wherein the firstintermediate discrete layer and the second intermediate discrete layereach comprise the SAP, the TA_(D) and the TA_(R) combined.
 26. Theabsorbent system of claim 19 further comprising a first intermediatediscrete layer and a second intermediate discrete layer, wherein thefirst intermediate discrete layer is disposed between the top discretelayer and the absorbent composite, and wherein the second intermediatediscrete layer is disposed between the absorbent composite and thebottom discrete layer; wherein the top discrete layer and the bottomdiscrete layer each comprise substantially only the SAP; wherein theabsorbent composite comprises substantially only SAP; wherein the firstintermediate discrete layer comprises substantially only the TA_(D); andwherein the second intermediate discrete layer comprises substantiallyonly the TA_(R).
 27. The absorbent system of claim 19 wherein theabsorbent system is present in an absorbent article which furthercomprises a topsheet and a backsheet, wherein the absorbent composite isdisposed between the topsheet and the backsheet.
 28. The absorbentsystem of claim 19 wherein the absorbent system is present in anabsorbent article selected from personal care absorbent articles,health/medical absorbent articles, household/industrial absorbentarticles or sports/construction absorbent articles.